PIRATOSAURUS. 29 
The measurements of the largest and smallest specimens, or the first and last of 
the series, are as follows :— 
LARGEST. SMALLEST, 
Lines. Lines. 
Length of the vertebral body. . : ( : ; d . 385 31 
Breadth of articular extremities : : ; : , : . 50 41 
Height of articular extremities . . - - : . - . 39 28 
Width of spinal canal - E : ; ; j : : yey 8 
It is probable that the vertebra, above described as lumbars, may be regarded in 
part as representing sacrals and caudals. Both dorsals and lumbars bear some 
resemblance to the corresponding vertebree of Cetaceans, except that in these the 
transverse processes project from the middle of the sides of the body of the 
lumbars instead of the lower part. The long series of vertebrae of Cimoliasaurus 
consisting of lumbars apparently gradually merging into caudals, perhaps indicate 
the absence of a true sacrum and posterior extremities, as in Cetaceans. 
I cannot avoid the suspicion that the specimens referred to Cimoliasaurus mag- 
nus do not belong to the same great reptile as those considered as characteristic of 
Discosaurus vetustus. 'The supposed caudals of the latter I have suspected to be 
anterior cervicals notwithstanding the apparent provision for the articulation of 
chevron bones. If all the vertebral specimens be viewed as belonging to one 
animal, they represent cervicals, dorsals, and lumbars of Discosawrus, otherwise they 
represent a cervical and caudals of the latter, and dorsals and lumbars of Cimoli- 
asaurus. 
The vertebrae described as caudals of Discosaurus have almost the same size and 
nearly the same form as the smaller lumbars or caudals attributed to Cimoliasaurus. 
A rib of proportionate size, coosified with the costal pit in the former, would give 
them a striking resemblance to the latter, except that in Cimoliasaurus the costal 
or transverse processes project from the lower part of the sides of the body, whereas 
in Discosaurus the costal pits are situated at the middle of the sides of the body. 
The vertebrae, however, differ in other important particulars. Besides the absence 
of the conspicuous inflections (supposed to have been intended to accommodate 
chevron bones) in the caudals of Cimoliasaurus the body beneath is nearly level 
between the transverse processes, while in Discosaurus it is strongly convex in the 
corresponding position. 
No portions of the skull nor specimens of teeth have been discovered which, 
with any probability, could be referred either to Discosaurus or Cimoliasaurus. 
PIRATOSAURUS. 
Piratosaurus plicatus. 
I recently received from the Smithsonian Institution, for examination, a small 
collection of fossils, which, in a note accompanying the specimens, are stated to 
have been obtained from the drift of Red River Settlement, about fifty miles south 
of Selkirk Settlement, and are further labelled as from the Red River of the North. 
The specimens consist of a peculiar Crocodilian tooth, and others agreeing in form 
with those referred to Otodus appendiculatus, Corax appendiculatus, and Ptychodus 
