10 



Although I procured numerous cervical vertebrae, there are but 

 few which exhibit the anteroinferior facet for supposed hypapo- 

 pli3'sis, already described. The position of this vertebra was in 

 front of the first cervical which displays a parapophysis, and is, 

 on this account, likely to be the axis or the third cervical vertebra. 

 It is the more probably the axis, as there is no other among the 

 large number of vertebrae in my collection which can be referred 

 to that position. Its anterior articular face is smooth and like 

 the posterior, showing that the odontoid bone was not coossified 

 with it. Now in the Crocodilia the odontoid bone is united with 

 the anterior extremity of the axis by suture, which may become 

 coossified with age, while the free hypapophysis is wanting. In 

 the streptostylicate orders the hypapophysis is present, and the 

 odontoid is above it, but united to the axis by suture. On the 

 other hand, in the Rhynchocephalia, the axis is coossified with both 

 odontoid and hypapophysis, and a few succeeding vertebrae possess 

 free hypapophyses. Thus it is possible that I am yet unacquainted 

 with the axis of Champsosaurus. 



One entire rib and the heads of several others are all that were 

 obtained. The former is from the anterior part of the dorsal 

 series, and is stout and short. The head is truncate and com- 

 pressed, its articular face is contracted, forming a narrow figure 

 eight. The shaft is obliquely flattened. The extremities are sepa- 

 rated from the lateral surfaces by a narrow angle, as though capped 

 with cartilage in life, as in the Pythonomorpha. 



Bones of the extremities are very rare. One fragment resem- 

 bles the proximal end of a crocodilian tibia, and another is like 

 the distal half or more of the tibia of the same type. 



There is considerable resemblance between the vertebra? of this 

 genus and those of Hyposaurus, Ow., from Cretaceous No. 5, of 

 New Jersey, but the relations of the axis and atlas in that genus 

 are as in other Grocodilia, and not like those seen in Champso- 

 saurus. The absence of sacrum precludes the possibility of regard- 

 ing this form as dinosaurian. It rather seems to share some 

 rhynchocephalian characters with general amphiplatyan crocodi- 

 lian resemblances. The shortness and robustness of the thoracic 

 ribs is a feature quite unique, and reminds one of the Batrachia. 

 The teeth are unknown in their true relations, but there are several 

 types in the collections which may be found to belong here. These 

 are of the rhizodont character. 



