(878. | Geology and Paleontology. 633 
GEOLOGY AND PALAONTOLOGY. 
THE VERTEBRA OF Racuiromus.—This genus of esas 
donts was chia in this journal for May, 1878 (p. 328), 
from vertebre. that date, the reception of other specimens 
enables me to add some points to the definition already given. 
There is an element representative of the centrum wedged in 
between the superior external angles of adjacent intercentra, as 
in Zrimerorhachis. These, as well as the intercentra, differ from 
those of that genus in their greater degree of ossification, which 
is so far complete as to greatly contract the canalis cord@ dorsalis. 
The central elements of opposite sides do not unite on the middle 
line, although in contact. The neurapophysis is produced down- 
wards and outwards, terminating in the simple diapophysis, with 
rib articulation. The inferior articular faces of the arch are two 
on each side, one for the central element in front, and the other 
for the one behind it. The whole is surmounted by a continuous 
neural spine, which is expanded at the summit in the known 
species. The ilium is a subspatulate flat bone, with its rather 
thin oval proximal extremity directed backwards, and extending 
across three centra 
It is probable that the vertebra: of the genus Lryops (Pr 
S. 1878, 520), and perhaps those of all the true Labyrinthodontia, 
are constituted as in Rhachitomus —E. D. Cope. 
THE Positrion OF Diprerus.—Dr. R. H. Traquair has recently 
studied the structure of: Dipterus and has determined several 
points which are essential to a knowledge of its Sasi posi- 
tion. He finds that in its suspensorial apparatus it agrees with 
Ceratodus as well as in its palopterygoid bones. He infers that 
the character of the pectoral fins is identical with that of Cerato- 
dus. The skull differs from that of the genus in question in the 
greater degree of ossification of all its parts. Dr. Traquair places 
Dipterus definitely among the Dzpxoi, as already done BEBET 
y Günther. He also regards Paledaphus as a mem 
same sub-class; and discovers that Chirodus is aod on the 
splenial tooth of a Platysomid fish. 
A FOSSIL WALRUS DISCOVERED AT PorRTLAND, MAINE.—The 
larger part of the skeleton of a walrus, including the skull with 
tusks over five inches long, and all but two of the teeth, has 
lately been unearthed from the Quaternary Clays of Portland, 
Maine. It was partially imbedded in a layer of blue clay a foot 
in thickness, overlaid by a layer of lighter clay two feet two 
inches thick, ‘containing casts and shells of Mya arenaria, Macoma 
subulosa, Mytilus edulis, Cardium (Serripes) granlandicum, Astarte 
striata , Saxicara distorta, n antigua, Leda tenuisulcata, L. 
truncata, Natica clausa, and pusilla, and Balanus. The skeleton 
n the museum of the Portland Society of Natural History. 
1 See Proc, Amer. Philos. Soc., 1878, p. 526. 
