Cope.] lOO [Nov. 2, 



remains. The vertebra which is best preserved, and which may be regarded 

 as typical, is probably from the caudal series, and is thus well contrasted 

 with the corresponding typical vertebra of the longer known species. 



On this vertebra there is no trace of diapophysis, and the neurapophysis 

 rises from the external side of the superior face. The wall of the neural canal 

 is not preserved, but the inference is that the diameter of the latter is large. 

 This fact and the absence of definite chevron articulations leads me to doubt 

 the caudal position of the vertebra ; but the usual marks of the dorsal and 

 cervical vertebrae are totally wanting from it. As in 0. heteroclitus, the 

 foramen chorda dorsalis is large, its diameter being one-third of the total. 

 The articular faces descend steeply into it, that of one extremity more so 

 than the other. The rim of the latter face is beveled outwards, the plane 

 thus produced appearing on the inferior face something like the united 

 faces of the chevron bones. 



The centrum is a little deeper than wide, and the inferior face is trun- 

 cate so as to give a subquadrate outline. The inferior plane is concave, the 

 concavity being divided by a longitudinal rib. The sides are somewhat 

 concave, with a longitudinal rib at the middle. Diameters of centrum : 

 vertical .010; transverse .009 ; longitudinal .008. Width of inferior plane 

 .005 ; width above, including neurapophyses, .008. 



As compared with G. heteroclitus this species differs in the presence of 

 parallel ridges enclosing a median fossa on the inferior side of the centrum. 

 The small size may be here considered, but it is uncertain whether the 

 two animals represented by the vertebrae are fully grown. 



This reptile is named in recognition of the services of William Gibson of 

 Newport, la., who has added a number of interesting facts to the geology 

 of the Wabash region. 



Cricotus discophorus, Cope, sp. nov. 



A vertebra, representing an animal as large as the (7. heteroclitus, presents 

 characters so much at variance with those ot the latter as to require special 

 notice. Three other vertebrae of smaller size present similar features. 



The centrum is disciform, with very short antero-posterior diameter, 

 which is, however, greater at one part of the surface than at the opposite 

 point. The foramen chordae dorsalis occupies about one-fifth of the trans- 

 verse diameter, which is subequal in all directions. The articular faces of 

 the centrum are slightly concave. The margin of that of one side is beveled 

 for the superior two-thirds of the circumference, the bevel running out 

 below by turning into the articular face. The latero-inferior border of the 

 latter turns out into an obtuse angle at this point. The superior part of 

 the bevel runs into the lateral face of the centrum. The attachment of the 

 neural arch is obscure or wanting in the specimen, and the same is true of 

 any facet for chevron bones. 



Diameter of articular face J vei ica 



l transverse 025 



Length of centrum below 009 



above 007 





