tions become increased-as the tears, saliva, urine and mucus of the air-passages, which effect appears to be owing to the paralysis of the vascular nerves and consequent dilatation of the vessels caused by the poison.

16. In mammalia urari causes death by paralysis of the respiratory nerves and suppression of the respiration, which brings on convulsions in these animals as a collateral effect. In frogs the final extinction of the functions may also be partly ascribed to suppressed action of the lungs and defective oxidation of the blood, which at length renders the heart unfit to perform its office; but it must be observed that in this case the cause of death is not so plain, inasmuch as in these animals the functions are in a great degree independent of the pulmonary respiration.

II. STRYCHNIA.

Some experiments with strychnia (the acetate) gave the following results :

1. Strychnia has not the least influence on the peripheral nerves through the blood, which is best shown by cutting the nerves before administering the poison.

2. Strychnia paralyses the motor nerves of the voluntary muscles by exciting them to too energetic action, a paralysis which may be compared to that caused by powerful electric currents acting upon the nerves. In frogs, when the tetanic spasms are over, the nerves often show no trace of excitability; in mammalia they generally retain it in a slight degree, but never show the same energy of action as when uninjured.

3. Strychnia does not affect the sensory nerves.

4. The heart is not affected by strychnia, not even during the tetanic spasms, with the exception only that its pulsations are sometimes a little slower during the tetanic state. On the contrary, the lymph-hearts of frogs contract themselves as soon as the tetanus begins, and remain in this state as long as the spasms last.

5. The tetanic fits can be brought on in two ways; first, through the sensory nerves, which, by irritating the grey substance of the spinal cord, produce the tetanic contractions as reflex movements; and, secondly, through the brain, which is not affected at all by strychnia and preserves its powers of volition and sensation. Accordingly, animals poisoned with strychnia try to move in the ordinary way, but every attempt brings on a tetanic fit, so that it is plain that the spinal cord may also be excited by the brain to its peculiar

actions.

6. If the tetanus produced by strychnia has been strong, the muscles are less irritable and pass much sooner into the state of cadaveric rigidity, which is very strongly marked, and seems to last longer than it generally does. The same early onset of rigidity may be observed in animals killed by tetanus excited by electricity.

"Researches on the Foraminifera."-Part II. By William B. Carpenter, M.D., F.R.S., F.G.S.

GEOLOGICAL SOCIETY.

[Continued from p. 295.]

March 11, 1857.-Colonel Portlock, R.E., President, in the Chair. The following communications were read :—

1. "On the Dichobune ovina, from the Upper Eocene of the Isle of Wight." By Professor Owen, F.R.S., F.G.S.

3-3

3-3'

1

4-4

3-3

This paper comprised a detailed description of the lower jaw and teeth of an Anoplotherioid quadruped (Dichobune ovina, Owen), of the size of the Xiphodon gracilis, Cuvier, and belonging to the family that includes Dichobune and Xiphodon. The dental formula, as shown by these teeth, and by the evidence on their crowns of the presence of the teeth of the upper jaw, is the typical one in diphyodont mammalia, viz. incis. can. premol. molars, 344. Professor Owen, having described the differences of the species under notice from the allied species D. cervinum, concluded with some remarks on the relations of the genera Xiphodon and Dichobune, as illustrated by their dental organs; and pointed out that the small anoplotherioid Microtherium, so much in some respects resembling the Chevrotains of Java, &c., but possessing persistent upper incisor teeth, probably differed also from the Ruminants in having a still more simplified structure of the stomach than is presented even by the Chevrotains (Tragulus, in which the third bag or psalterium is suppressed). Thus nearly all of the known eocene artiodactyle herbivores are separable from the Ruminants; and of the very few that remain, the dental evidences are as yet incomplete. Further, the gradations of dentition displayed by the extinct even-toed hoofed herbivores above referred to go far to establish the natural character of the group Artiodactyla.

2. "On two species of the fossil Mammalian genus Plagiaular from Purbeck." By Dr. H. Falconer, F.R.S., F.G.S.

The author first alluded to the interesting relics of Mammalia (Spalacotherium) discovered some time since by Mr. W. R. Brodie, in the cliffs of Durdlestone Bay, near Swanage, and described by Professor Owen in the Journal of the Society (vol. x. p. 420, &c.). He then mentioned that Mr. Brodie had since made some important additions to this Purbeck fauna (including the Triconodon); and that Mr. S. H. Beckles had more recently obtained numerous additional evidences of mammalian animals (chiefly in the condition of lower jaws), besides various valuable reptilian remains in the same thin freshwater deposit which had yielded the fossil above referred to, and was still energetically occupied in the research. Among the specimens found by Mr. Beckles, are some portions of the lower jaws of two species of a mammalian genus, which is best represented among existing forms by the Hypsiprymnus or Kangaroorat. Dr. Falconer names the fossil genus Plagiaulax, —an abbreviation for "Plagiaulacodon," from λáyios oblique, and avλat groove; having reference to the diagonal grooving of the premolar teeth. With regard to these two species (P. Becklesii and P. minor), satisfactory evidence has been obtained as to the characters of the Phil. Mag. S. 4. Vol. 13. No. 87. May 1857. 2 D

lower jaw: the dental formula being-incisors, 1-1; canines, 0-0; premolars, 3-3 and 4-4; molars, 2-2; = 12 and 14 in all. The author then entered into a very full detailed description of the teeth and jaw in each of the two species. Plagiaular characteristically differs from Hypsiprymnus,—1st, by the obliquity of the grooves on its premolars, the latter genus having the analogous teeth vertically grooved; 2ndly, by having only two true molars in each ramus of the jaw, instead of the usual four and occasional three, belonging to recent marsupials; 3rdly, by the considerable salient angle which the surfaces of the molar and premolar teeth form, instead of presenting a uniform level line; 4thly, by the very low relative position of the articular condyle. In P. Becklesii the two incisor teeth were large and robust, projecting upwards at a considerable angle, and the ramus of the jaw was remarkably short and deep. In P. minor the incisors were more slender, pointing less suddenly upwards, and the ramus was narrower and more curved. Dr. Falconer more especially infers the marsupial characters of the genus,-1st, from its Hypsiprymnoid resemblances in the grooved premolars and the relative size and position of the incisors; 2ndly, from the raised and inflected fold of the posterior and inner margin of the ramus; 3rdly, the form and characters of the symphysial suture.

The author dwelt upon the peculiarly small number of the true molars in this genus,-presenting, as it does, a marked special suppression in these organs, and so offering the most specialized exception, amongst the marsupiata, fossil or recent, from the hitherto accepted rule of the older vertebrate forms presenting the least departure from the archetypal plan. He noticed also the interesting fact, that the crowns of the molars of Plagiaulax presented an unmistakeable and close resemblance to those of the minute teeth of the Microlestes from the Triassic Bone-bed of Wurtemberg. Lastly, Dr. Falconer alluded to the fact of little lower jaws and small isolated bones forming so large a proportion of the mammalian remains from this thin Purbeck freshwater bed; whilst more or less perfect skeletons of aquatic or amphibious reptiles occurred in the same deposit; and he stated that not only had he observed that in the tanks in India the bones of small animals were uniformly wafted to the margin, but that M. Lartet had lately pointed out to him that in the rich Falunian deposit of Sansan, the skeletons of the large terrestrial animals were found in certain parts of the lacustrine beds, whilst in other parts, probably the old marginal deposits, the little bones of frogs, shrews, &c., could be collected by the handful. The author could not therefore but hope that further explorations, by opening out the stratum where it was originally deposited in deeper water, would yield even richer supplies of still larger mammals. March 25, 1857.-Colonel Portlock, R.E., President, in the Chair. The following communications were read :

1. "On some Fish-remains from the neighbourhood of Ludlow." By Sir P. G. Egerton, Bart., M.P., F.G.S.

This paper comprised descriptions of some specimens of fossil

fishes díscovered by Mr. Salwey in the Old Red Sandstone of Acton Beauchamp, and others by Mr. Lightbody in the upper bone-beds near Ludlow. From the first-named locality the author described a portion of a cephalic carapace, indicating a large and new species of Cephalaspis (C. Salweyi). Another new species of Cephalaspis (C. Murchisoni) was founded on two specimens obtained by Mr. Lightbody in a bed below the paper-mill on the river Teme at Ludlow; and a third new species (C. ornatus) was described from specimens from dark micaceous shales in the Hereford Railway Cutting at Ludlow. The same shales have afforded two specimens of a very small Cephalaspid of great interest. These are of the size of a fourpenny piece, and have a general resemblance to Cephalaspis, except in the peculiarity of having behind the cephalic shield, and united to its posterior margin by a distinctly marked suture, a broad plate divided into lateral halves by a prolongation of the occipital crest. The author, having stated his reasons for regarding these specimens as adult and not embryonic individuals, gave this new Cephalaspid form the generic title Auchenaspis (on account of its nuchal plate), and described it under the specific name of A. Salteri. In conclusion, some other ichthyic remains, referable to Plectrodus and Onchus, were enumerated as having been collected by Mr. Lightbody in the railway-cutting and in the River-bed near Ludlow.

2. "Note on the relative position of the Strata containing the Ichthyolites described by Sir P. Egerton." By Sir R. I. Murchison, V.P.G.S.

The section of the railway-cutting north of Ludlow exhibits an upcast mass of upper Ludlow rock a few feet thick and surmounted by micaceous sandstone and red marl. It is distinct from, and younger than the well-known Ludlow bone-bed, which is overlaid in order by the grey-coloured Downton Castle sandstone. Though higher in the series, still this band at the railway-cutting contains some characteristic fossils of the lower bone-bed, such as the Plectrodus mirabilis ?, Onchus Murchisoni?, and Lingula cornea. At the same time it contains forms unknown in the lower beds, viz. Cephalaspis ornatus, Auchenaspis Salteri, an Onchus or Byssacanthus, Pterygotus anglicus, and Eurypterus pygmæus.

The section obtained on the right bank of the Teme, south of Ludlow (between Ludford and the paper-mill), indicates that the Ludlow bone-bed, dipping gently to the S.E., is covered by grey strata representing the Downton Castle stone, which pass under brownish, micaceous, thin-bedded sandstones, and these, to the east of the cornmill, are succeeded by red marl with cornstones. The fossiliferous band exposed at the railway, though probably included in this section, is not seen on account of denudation and superficial gravel; but another and still higher fossiliferous micaceous band, discovered on the river-bank by Mr. Lightbody, afforded the Cephalaspis Murchisoni described by Sir P. Egerton, together with Plectrodus, Onchus Murchisoni, and Lingula cornea. These tilestone-beds are succeeded by the red marls, sandstones, and cornstones with Cephalaspis Lyellii, Pteraspis Lloydii, &c. From the mingling of peculiar cephalaspid forms with the Lingula cornea and Upper Silurian ichthyolites in

these tilestone-beds of Shropshire and Herefordshire (which have about 40 or 50 feet of thickness), Sir Roderick is inclined to regard them as true "passage-beds between the Silurian and Devonian systems, and to be classed with the lower or the upper system according to the prevalence of certain fossils.

3. "On the occurrence of Mastodon Bones in Chile." By W. Bollaert, Esq. Communicated by Prof. Owen, F.G.S.

The author observed, that hitherto there have been few if any fossil bones of large quadrupeds found on the western side of the Andes. During his travels in South America, he had diligently searched for information on the subject; and he had learnt from Mr. G. Smith, H.B.M.Consul at Santiago de Chile, that some elephantine bones had been met with in digging a trench to drain the Lake Taguatagua, in the province of Colchagua, about 45 leagues due south of the capital, and at an elevation of 2300 feet above the level of the Pacific Ocean. This lake occupied a circular and crater-like depression among the third range of hills running N. and S. through Chile. The skeletons of two animals were found at the depth of about 30 feet below the margin of the lake.

Some of the teeth (referred to Mastodon by Don V. Bustilos) are in the Museum at Santiago, and fragments of the femur and tibia brought home by Mr. Bollaert have been also referred to Mastodon by Prof. Owen.

T

LIII. Intelligence and Miscellaneous Articles.

EXPERIMENTS ON THE ARTIFICIAL FORMATION OF THE HYDRATED CARBONATES OF THE EARTHS AND METALS. BY A. DAMOUR. HE metallic and earthy carbonates have already been obtained artificially in a crystalline state by various processes. Thus when a soluble salt and an alkaline carbonate are exposed to a high temperature in a close vessel, double decomposition takes place, giving origin to an insoluble and crystalline carbonate. A soluble salt may also be precipitated by an alkaline bicarbonate in water supersaturated with carbonic acid. This mixture, placed in an apparatus which only allows the carbonic acid to escape slowly, and exposed to a more or less elevated temperature, gives origin to anhydrous crystalline carbonates. These processes are due to the experiments of M. Senarinont.

The solution of an acid salt may be poured into a saturated solution of an alkaline bicarbonate, when the carbonic acid being in excess exerts a solvent action on the carbonates, and by its slow evaporation under the simple pressure of the atmosphere, allows the dissolved matters to separate and crystallize. In this manner, sometimes simple, sometimes double, hydrated carbonates are obtained. This is the method of M. H. Deville.

The author has undertaken a series of experiments on the direct action of carbonic acid upon the earthy bases and metallic oxides. The apparatus employed consists of a glass vessel in two compartments, such as is used for the artificial preparation of Seltzer water. The oxide or recently prepared carbonate is suspended in distilled