Example, Triton cutaceus.

Description.-Shell ovate, ventricose-depressed, cingulated, tuberculato-nodose, yellow-rufescent; the belts rather prominent, separated by a furrow; the whorls above angulato-tuberculate, rather flattened above; canal short, umbilicated; the outer lip notched within.

junction of the two lips. (Genus Aquillus, De Mont- | verse, subgranulated, low ridges, the interstices between fort.) which are longitudinally striated; the whorls armed with one row of sharp tubercles, the middle of which are the longest, the other ridges of the body whorl obsoletely tuberculated here and there; the columellar lip expansive and foliated, and the margin of the outer lip expanded and thin; the aperture ovate, very strongly and thickly furrowed, of a rich orange-colour, and terminating above in a deep foliated sinus, which extends beyond the varix. (Brod.) Locality.-The Mauritius.

Locality.-The Atlantic Ocean.

D. Species like those of section C, but whose aperture is closely narrowed by a callosity and irregular teeth. (Genus Persona, De Montf.)

Example, Triton Anus, the Grimace of collectors. Description.-Shell ovate, ventricose-gibbous, distorted, flattened beneath; nodulous above, subcancellated, white, spotted with rufous; the aperture narrowed, sinuous, irregular, ringent; the lip very much toothed; the canal short and recurved.

Locality-The East Indian Seas. Tritons have been found on various bottoms at depths ranging from the surface to thirty fathoms.

The number of living species recorded by Lamarck amounts to fifty-one. Mr. G. B. Sowerby has described eight additional species, and Mr. Broderip the same number brought home by Mr. Cuming. Lamarck describes three fossil species, all from Grignon. M. de Biainville states that one of the species has its analogue. Defrance makes the number of fossil species ten, one from the Plaisantin, an analogue according to Brocchi. M. Deshayes in his tables, published before the descriptions of Mr. Sowerby and Mr. Broderip, makes the number of living species of Triton 43 and of fossil (tertiary) 25. Of these last, he records Tritones nodiferus, Lampas, Scrobiculator, succinctus, clathratus, and unifilosus as both living and fossil (tertiary). Struthiolaria. (Lam.)

Generic Character.

Shell oval, the spire elevated, the aperture oval and wide; canal very short, very much notched; right lip sinuous, not toothed, furnished with a bourrelet; columellar border callous, extended; a sinus at the posterior union of the two lips.

Operculum horny.

Example, Struthiolaria nodulosa.

Description.-Shell ovate-conical, thick, transversely striated, white, painted with undulated, longitudinal, saffron-coloured flame-like lines; whorls angulated above, flattened on the upper side, nodulous at the angle; the sutures simple, the outer lip luteo-rufescent within.

Locality. The seas of New Zealand.

Lamarck records two living species. M. Deshayes, in his tables, also makes the number of living species two; and he records one fossil (tertiary), with a query, from Paris. Ranella. (Lam.)

Generic Character.

Shell oval or oblong, depressed, having only two varices situated laterally; aperture oval; canal short, and a sinus at the union of the two lips, backwards.

A. Non-umbilicated species. (Genus Bufo, De Montf.) Example, Ranella granulata.

Description.-Shell ovate-acute, girt with close-set granulated striæ, pale saffron colour, zoned with fulvous; columella sulcated: outer lip thick and toothed.

Locality. The East Indian Ocean.

B. Umbilicated species.

Example, Ranella foliata.

1524

Ranella foliata.

Ranella have been taken on different bottoms at depths varying from the surface to eleven fathoms.

Lamarck describes fifteen living species. M. Deshayes has described another; and Mr. Broderip nine new species, eight of which were brought home by Mr. Cuming. M. de Blainville states that there is but one fossil species, but allows that Defrance admits five, three of which, from Italy, are identical. M. Deshayes, in his tables, gives the number of living species as nineteen, and of fossil (tertiary) as eight: of these last he records Ranelle gigantea, granulata, pygmæa, and tuberosa, as living and fossil (tertiary). Murex. (Linn.)

Generic Character.-Animal furnished with two long and approximated tentacles; mouth without jaws, but armed with hooked denticles in lieu of a tongue; foot rounded, generally rather short; mantle large, often ornamented with fringes on the right side only; branchiæ formed of two unequal pectinations; anus on the right side in the branchial cavity; orifice of the oviduct on the right side at the entrance of the same cavity; orifice of the deferent canal at the end of the exciting organ, on the right side of the neck.

Shell.-Oval, oblong, more or less elevated on the spiral side, or prolonged forwards; external surface always interrupted by rows of varices in the form of spires or ramifications, or simply tubercles, generally arranged in regular and constant order; aperture oval, terminated anteriorly by a straight canal, which is more or less elongated and closed; right lip often plaited or wrinkled; columellar lip often Operculum horny.

callous.

A. Species with a very long and spiny tube. (Thorny
Woodcocks of collectors.)

Example., Murex Tribulus, Linn. (Murex tenuispira,
Lam.)

Description. Shell ventricose anteriorly, the tube very long, elegantly spired throughout its length, the spires set in triple order, each row at regular intervals, greyish or purplish grey; the spires very long, thin, rather closely set, and somewhat hooked; body of the sheil transversely sulcated and striated; the spire prominent.

Locality. The Indian Ocean; Moluccas.

This is the Venus's Comb of collectors, and when perfect is a most delicate and striking shell.

B. Species with a very long tube and without spines. (Genus Brontes, De Montf.)

Example, Murex Haustellum (Snipe's or Woodcock's head of collectors).

Description.-Shell anteriorly ventricose, naked, scarcely armed, fulvous inclining to red, lineated with bay; body of the shell rounded and furnished with three or more ribs Description.-Shell ovate conical, ventricose, not com- between the varices; the tube very long and slender; the pressed, of a flesh or pale rose-colour; with frequent trans-spire short; mouth roundish, red.

this kind are extremely rare in the fossil shells of any older formation. In the green-sand and oolite they have been noticed only in those few cases where they are accompanied by the shells of equally rare carnivorous mollusks; and in the lias and strata below it, there are neither perforations, nor any shells having the notched mouth peculiar to perforating carnivorous species. It should seem from these facts that, in the economy of submarine life, the great family of carnivorous trachelipods performed the same necessary office during the tertiary period which is allotted to them in the present ocean. We have further evidence to show that in times anterior to and during the deposition of the chalk, the same important functions were consigned to other carnivorous mollusks, viz. the testaceous cephalopods: these are of comparatively rare occurrence in the tertiary strata and in our modern seas; but throughout the secondary and transition formations, where carnivorous trachelipods are either wholly wanting or extremely scarce, we find abundant remains of carnivorous cephalopods, consisting of the chambered shells of nautili and ammonites, and many kindred extinct genera of polythalamous shells of extraordinary beauty. The molluscous inhabitants of all these chambered shells probably possessed the voracious habits of the modern cuttle-fish; and by feeding like them upon young testacea and crustacea, restricted the excessive increase of animal life at the bottom of the more antient seas. Their sudden and nearly total disappearance at the commencement of the tertiary era would have caused a blank in the" police of nature," allowing the herbivorous tribes to increase to an excess that would ultimately have been destructive of marine vegetation, as well as of themselves, had they not been replaced by a different order of carnivorous creatures, destined to perform in another manner the office which the inhabitants of the ammonites and various extinct genera of chambered shells then ceased to discharge. From that time onwards we have evidence of the abundance of carnivorous trachelipods, and we see good reason to adopt the conclusion of Mr. Dillwyn, that in the formation above the chalk the vast and sudden decrease of one predaceous tribe has been provided for by the creation of many new genera and species possessed of similar appetencies, and yet formed for obtaining their prey by habits entirely different from those of the cephalopods. The design of the Creator seems at all times to have been to fill the waters of the seas and cover the surface of the earth with the greatest possible amount of organised beings enjoying life; and the same expedient of adapting the vegetable kingdom to become the basis of the life of animals, and of multiplying largely the amount of animal existence by the addition of carnivora to the herbivora, appears to have prevailed from the first commencement of organic life to the present hour.' (Bridgewater Treatise.)

Sİ'RACUSE. [SYRACUSE.]

SIRE'DON, Wagler's name for the AXOLOTL. Since that article was written, further information has been obtained relative to the structure of this genus of perennibranchiate Batrachians. The form and character of the teeth, as given by Professor Owen, will be found in the article SALAMANDRIDE, vol. xx., p. 328, and we avail ourselves of this opportunity to introduce a reduced copy of the figure of the animal, lately published by MM. Duméril and Bibron, to whose excellent work on Reptiles we refer for the latest particulars known.

may have some notion of its relationship to the other perennibranchiate Batrachians.

Cuvier then remarks that the Axolotl approaches nearly to the Salamander, and especially to its larva. The cranium of the Axolotl is indeed more depressed; its sphenoïd bone wider and flatter; the bones of the nose proportionally smaller; the ascending apophyses of the intermaxillary bones longer and narrower; but, especially, in lieu of those large and fixed bones which Cuvier calls vomers or palatines, there are two oblong plates detached from the cranium beset with teeth in quincuncial order, and continuing them selves with the pterygoïds, which reach them because they are longer than in the Salamander, and which also carry teeth in front on their external edge. Behind, these pterygoïds are widened, without always articulating themselves to the sphenoïd, as in the Salamander of the Alleghanies. [SALAMANDRIDE, vol. xx., p. 332.] The space between the orbital and the petrous bone is also more considerable than in the Salamanders. The lower jaw has a regular dental portion forming the symphysis and the greatest part of the external surface, and armed all along its superior edge with small, fine, and pointed teeth; an articular portion, which doubles the posterior part of the internal surface of the preceding, forms the posterior angle and carries the articular tubercle; lastly, there is a true opercular bone, long and delicate, covering at the internal surface the interval of the two preceding, but furnished throughout with very small pointed teeth arranged in quincuncia. order. And this is the structure which we find in the SIREN, with this difference, that the dental portion in the latter has no true teeth, which are only seen on the opercular bone.

In all the Axolotls that Cuvier examined, the branchial apparatus was cartilaginous. It consisted of two suspensory branches, or anterior horns, affixed to the cranium under the fenestra rotunda, carrying an unequal piece, to which two lateral branches were attached on each side: the first carried the first arch of the branchiæ; the second, the three others. The first of these arches had dentilations on its posterior border; the two intermediate ones, on both their borders. Under the unequal piece was one which went backward, and whose extremity was bifurcated.

When Cuvier wrote this description (in the Ossemens Fossiles), he thought that this animal was the larva of some unknown Salamander; but in his last edition of the Règne Animal he corrected this conjecture, and placed it where all zoologists now place it, among the Batrachians.

SIREN (Zoology), a genus of Perennibranchiate Batrachians.

Generic Character.-Form elongated, nearly like that of the eels; branchial tufts three on each side; no posterior feet, nor any vestige of a pelvis; head depressed; gape of the mouth not wide; muzzle obtuse; eye very small; the ear concealed; lower jaw armed with a horny sheath and several rows of small teeth; the upper jaw toothless; but numerous small, pointed, retroverted teeth occur on the palatal region. [SALAMANDRIDE, vol. xx., p. 328.]

Dr. Garden appears to be the first who called attention to this form, which is declared by Cuvier to be one of the most remarkable of the class of Reptiles, and indeed of the whole animal kingdom, from the anomalies of its organization, and its apparent relationship with different families, and even classes. Dr. Garden (1765-1766) sent a description of this reptile to Linnæus and Ellis, and the former, relying upon Dr. Garden's assurance that the Siren did not change its form, established an additional order for it in his class Amphibia, with the name of Meantes.

Pallas, Hermann, Schneider, and Lacépède however saw, as Cuvier remarks, nothing more in the Siren than the larva of some large unknown Salamander; whilst Camper, followed by Gmelin, went so far as to give it a place among the fishes. The latter arranges it at the end of the Eels, under the name of Muræna Siren. These differences of opinion sufficiently show the doubts which arose on the ex amination of this extraordinary form.

.

Cuvier, in 1807, satisfactorily established, in a memoir read to the Institute of France, and inserted in the 1st vol. of the Zoological Observations of Humboldt,' that whatever changes it might undergo, the Siren was a reptile sui ge bony framework differed essentially from that of the Salaneris, which never could have hind feet, and whose whole manders; that there was no probability that it ever changed its form or lost its branchia; and that the Siren is conse quently a true amphibian, which respires at will throughout

its life, either in the water by means of branchiæ, or in the air by means of lungs. This conclusion rested upon that solid basis which has given such value-a value daily becoming more appreciated—to the views of this great zoologist, his personal observations made on the osteology and splanchnology of the animal.

Dr. Garden had, in his correspondence with Linnæus and Ellis, come to the same conclusion from other evidence. Dr. Garden had observed the animal from the length of four inches to that of three feet and a half; he had satisfied himself that in the whole province there was not, with the exception of the alligator, any Saurian or Salamander which exceeded six or seven inches in length, and he had convinced himself that it was oviparous, and that it propagated without losing its branchiæ.

In 1766 Hunter, as we shall presently see, declared the Siren to be a complete form, on the most satisfactory evidence: the specimens dissected by him were brought from South Carolina in 1758.

That the Siren is a perfect animal belonging to the perennibranchiate batrachians is now admitted by all zoologists. Cuvier indeed remarks (Règne Animal), that the branchia of Siren intermedia and Siren striata have been regarded as not participating in their respiration, and that in consequence Mr. J. E. Gray has formed them into the genus Pseudobranchus. Cuvier however adds, that it is, nevertheless, not difficult to see on their lower surface folds and a vascular apparatus, the use of which does not appear doubtful to him; and that M. Leconte has satisfactorily demonstrated that both these species, as well as Siren lacertina, are perfect animals.

Cuvier remarks that the Siren should be judged of not after Amphiuma, but from itself. He accordingly procured some sirens, and saw an osteology so finished and so firm, that it was impossible to believe that they were not adult. The branchise of these individuals were perfectly entire, and their lungs completely developed, and rich in wellfilled vessels. No doubt therefore existed in his mind that the animals used both.

each a groove for the lodgment of the posterior point of two slender bones, which proceed beside each other to the end of the muzzle. At their sides are attached two other bones, which are slender and pointed backwards, and which descend and widen far in order to raise the anterior edge o the jaw. Cuvier takes the first for the nasal bones, and the others for intermaxillary bones. These last are toothless, but their edge is trenchant, and furnished, when the animal is alive or well preserved, as well as the edges of the lower jaw, with a sheath which is nearly horny, is easily detached from the gum, and has its analogue in the tadpoles of the frogs. [SALAMANDRIDE, vol. xx., p. 328.] Between them, at the end of the osseous muzzle, is an aperture, but not that of the nostrils. In the recent animal it is closed, and the nostril is pierced on each side on the outside of the intermaxillary bone. In the crocodile the intermaxillary adheres to the external side of the nasal bone, and all the reptiles, except the crocodile, have the nostril on the outside of the ascending apophysis of the intermaxillary bone; but the peculiarity in the Siren is, that the intermaxillary ascending to the frontal bone entirely separates the nasal bone from the frame of the external nostril. The maxillary bone excludes the nasal in the same way in the chameleon. A very small bone, suspended in the flesh below the external nostril, and without any tooth, is the sole perceptible vestige of the maxillary bone. The cavity of the nostril is covered below with a simple ligamentous membrane. The internal nostril is situated on each side, near the commissure of the lips, between the lip and the palatine teeth. All the lower part of the cranium and the face is composed of a large and wide sphenoïd, which extends from the occipital hole to the intermaxillaries. The sides of the cranium, in the orbital region and the front of the temporal bone, are closed by a single bone, in which are pierced, forward, the olfactory aperture; farther back, the optic hole, and another for the first branch of the fifth pair, and probably for the small nerves of the eye. The inferior surface of this lateral bone forms part of the palate at the sides of the sphenoïd bone. It is plain that it performs the functions of He observes, that it had been objected that it would be the orbital part of the sphenoid bone, or what has been impossible for these animals to respire air without ribs or called the anterior sphenoïd, and that it fulfils in part those diaphragm; and without the power possessed by the tor- of the ethmoïd. Between it and the petrous bone is a great toises and frogs to cause it to enter by the nostrils, in order membranous space, in which is pierced the hole for the rest that, so to speak, it might be swallowed, because the nostrils of the fifth pair of nerves. The petrous bone and the lateral of the Sirens do not lead into the mouth, and the branchial occipital bone are perfectly distinct. It is in the petrous apertures must let it escape. But his own observations made bone only that the fenestra ovalis is pierced, or rather cut upon well-preserved individuals showed Cuvier that the nos-out, but the lower part of its frame is, nevertheless, comtrils in the siren do communicate with the mouth by a hole pleted by the lateral occipital and the sphenoïd. Its aperpierced, as in the Proteus, between the lip and the palatal ture, which is large, is directed a little downwards. In bone which carries the teeth. The membranous opercula the fresh state it is closed by a cartilaginous plate siof their branchia are muscular internally, and capable of milar to that in the Salamander. There is only a single hermetically sealing the apertures; then it is very easy for tympanic bone fitted obliquely by its posterior stem on the siren, by dilating its throat, to introduce the air into the superior surface of the petrous bone, and enlarging bethe mouth, and to force it afterwards, by contracting the low nearly like a trumpet, in order to furnish a large facet throat, into its larynx. Even without this structure of the to the lower jaw. Cuvier found neither mastoïdian, pterynostrils, the animal could produce the same effect by open- goïdian, jugal, superior occipital, nor basilary bone, and he ing its lips a little: a theory which Cuvier applies to the Pro- remarks that the occurrence of the two last is impossible, teus as well as the Siren. when the position of the suture, which separates the lateral occipital bones, is considered. To the palate, under the anterior and lateral part of the sphenoïd and orbital bones, are fitted two delicate plates beset with hooked teeth. They may be taken for the vestiges of vomers and of palatines, or, if it be preferred, of palatines and pterygoïdians; but Cuvier did not find sufficiently marked characters to warrant giving them those names. The first, which is the largest, has six or seven oblique rows of pointed teeth, making a kind of wool-card. Those of the middle have each twelve teeth; the anterior and posterior ones have less. second plate has four rows of similar teeth, each row consisting of from five to six.

The simultaneous existence, observes the same author, of a larynx and a trachea with a branchial apparatus not only permanent, but perfectly ossified in many of its parts, is also worthy of especial attention, and proves, as is evident in the frogs and salamanders, that the branchial apparatus is no other than a more complicated os hyoides, and not a combination of pieces proceeding from the sternum and larynx. He adds, that it is to the salamanders that the sirens approach most nearly by the structure of the head, although neither the general form nor the proportions of the parts have so near similarity.

Having thus given a general view of the conformation of this extraordinary animal, we proceed to a sketch of the details of its

ORGANIZATION.

Skeleton. The skull of the siren is narrowed in front by reason of the excessive reduction of the maxillary bones, which consist only of a very small osseous point. Behind there is a strong occipital crest on the parietal and petrous bones. The pieces which form the lower jaw, instead of being transverse like the branches of a cross, are directed obliquely forwards. The parietal bones occupy the greatest portion of the upper part of the cranium. They have each in front a point, expanding so as to lodge between them the posterior part of the principal frontal bones, which have P. C., No. 1866

The

The lower jaw of the Siren is composed of four bones on each side; one of which forms the symphysis and the trenchant border of the jaw, which it invests externally up to near its posterior extremity. One cannot, Cuvier observes, avoid taking it for the analogue of the dental portion, but it is not the portion which carries the teeth, and it has only its trenchant edge invested in the fresh animal with a horny covering, analogous to that which forms the edge opposed to the upper jaw. The posterior extremity of this trenchant edge, more elevated than the rest of the border of the bone, serves for the coronoid apophysis. The second bone forms the greatest portion of the internal surface and the posterior angle, and carries, above, the third, which is the VOL. XXI-I