PIRATOSAURTJS. 



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 .35 31 



Breadth of articular extremities ....... 50 41 



Height of articular extremities ........ 39 28 



Width of spinal canal 9 g 



It is probable that the vertebrae, 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 Discosaurus, otherwise they 

 represent a cervical and caudals of the latter, and dorsals and lumbars of Gimoli- 

 asatirus. 



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 gi-\'e 

 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. 



PIRATOSAIJRUS. 



Piratosanrus plicafns. 



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 otliers agreeing in form 

 with those referred to Otodus appendiculatus, Coi-ax appendicidatus, and Ptyclwdus 



