PROCEEDINGS OF GEOLOGTCA.L SOCIETIES. 
31 
Restoration of Pteraspis. 
My dear Sir, — Mr. Lankester, in referring in your last number to a 
paper of mine, in your November number, has given us two sketches of 
specimens of Pteraspis and the restoration of the test by Professor Huxley. 
Substantially, in the diagram of Professor Huxley, and in my second 
figure, we have the same elements ; and with my oilier figures Mr. Lan- 
kester does not interfere. I do not think, however, that his specimens are 
so decisive as he implies they are. In his first sketch there is no decided 
appearance of the central ridge or prolongation, and it appears to me, that 
there is a much larger portion of the test posterior to the cornua than what 
is to be discovered in the restoration of Professor Huxley. In his second 
sketch or specimen, I cannot see any certain evidence of the cornua at all, 
and therefore, from it also, I cannot gather how the spine or central pro- 
longation of the shield is related to them. Mr. Lankester informs your 
readers of first-rate specimens having been in the museums and in private 
collections for some years. Perhaps some of these may throw light on this 
point, and on other points connected with Pteraspis. 
Meantime, believe me, my dear Sir, 
Yours truly, 
Craigy Dec. 8. HuGH MlTCHELL. 
PEOCEEDINGS OF GEOLOGICAL SOCIETIES. 
Geological Society. — November IWi. — " On the Cambrian and Huro- 
nian Formations, with remarks on the Laurentian." By J. J. Bigsby, M.D. 
The author came to the conclusion that the Cambrian and the Iluronian 
are distinct formations, and the latter is very much tlie older. 
December ^rd, 1862. — 1. *' Description of the Remains of a new Enalio- 
saurian {Eosaurus Acadlanus), from the Coal Formation of Nova Scotia." 
By O. C. Marsh, Esq., M.A. Communicated by Sir C. Lyell, V.P.G.S. 
2. " Description of Anthracosaurus, a new genus of Carboniferous Laby- 
rinthodonts." By Professor T. H. Huxley, F.E.S., F.G.S. 
Anthracosaurus is distinguished from all other known Labyrinthodonta 
by the quadrate form and oblique position of the orbits, by the existence 
of elongated supratemporal foramina, and by the comparatively small 
number and large size of the teeth. The skull exhibited had an extreme 
length of 15 inches, and an extreme width of 12 inches. There are about 
30 maxillary, 2 vomerine, and 10 palatine teeth, which are ridged, and be- 
come flattened and two-edged towards their apices. The vomerine, pala- 
tine, and some of the anterior maxillary teeth are between 2 and 3 inches 
long, and from | to f of an inch in diameter at the base. The species ex- 
hibited was named A. Russelli, after its discoverer. Probably its entire 
skeleton had a length of not less than 6 feet. 
3. " On the thickness of the Parapean Formation near Buenos Ayres." 
By Charles Darwin, Esq., M.A., F.E.S., F.G.S. 
Some sections of Artesian wells sunk in this formation showed its entire 
thickness near Buenos Ayres to be about 210 feet. It was stated to rest 
upon various marine beds upwards of 100 feet thick, containing Oatrea 
Patagonica, Ostrca Alvarezii, Pecten Paranensis, etc. These reposed 
upon red calcareous clay, which was bored through to a depth of 213 feet 
more, contained no fossils, and is of unknown age. 
