Zoology. 141 
done so, Cimoliasaurus and Discosaurus would have become syno- 
nyms of Ples siosaurus, since no characters are known by which 
to distinguish them. As it is, I preserve the first, on the supposi- 
tion that its scapular arch, will be found to present the peculiari- 
ties belonging to Elasmosaurus. 
There are, however, several species included in Leidy’s last de- 
pt de a of Discos vetustus, as he suggests, but believing that 
‘the material was not sufficient to justify a separation,” he allowed 
them + remain tiger A portion of this material from New z er- 
sey belongs undoubtedly to nbd ceo magnus, and the other 
specimens (two vertebrx), which present a few peculiarities, are 
recorded in my Synopsis b Hatin Batrachia Reptilia, ete. sot Cimo- 
liasaurus vetustus. I presume that it is on these tw wo vertebrae 
that Leidy bases his teresa of Tieniscterses to Diesopaia 
If the evidence furnished by these was “ insufficient to justify their 
separation” from C. magnus, : is ic ane insufficient to Justify 
their Peay! to another genus. The proximal caudals of 
mosaurus and Ci aRaanris. are ‘daatioal: but the median ey. 
distal sandals of the two are quite distinct. ‘In E platyurus they 
Label a deep median groove beneath and a rib-like elevation on 
ach side. No such vertebre have been described as referable to 
angulate caudals among those referred to C. vetustus by Prot. 
ittle notice to LeConte’s report on the 
Geology of the Union Pacific R. R., southern shee bea 
was Baterssirrae constituted ; 2, that characters peparacing it from 
Plesiosaurus were not adduced; 3, that it was not distinguished 
from Cimoliasaurus; 4, that Disc scosaurus vetustus embraces at — 
pial, species, one of which is Os in er nie ong ; and, 5, t - 
cann: 
ir 0 and strange as it may appear, 
fee co. vioteatrels to prove that the Tape of that region is a 
they species from that of Panama, belonging, however, to the 
same cents MUsSiey Adie The most obvious differe 
in the development of the nasal and frontal bones, but those are 
confirmed e differences in the dentition, especially in 
form of the first premolar of each jaw. bones of the 
th Pp’ a 
young, compared with those of the corresponding age of EZ. Bairdii, 
* It can hardly be doubted seh the median and distal caudals of Cimoliasaurus 
are angulate beneath, to produce rminal planes for the chevrons, in accordance 
with the structure of Plesi secon 
