80 THE EXTINCT BATRACHIA, REPTILIA 



Several individuals of this, the largest of our cretaceous species, have been found, but only fragments preserved. 

 The cranial bones are smoother than those of the species of Holops, and the posterior nares are separated as above 

 mentioned. The cervical vertebras of this species are distinguished among those of its congeners by the lack of 

 inferior concavity, breadth of basal carina, complete bifurcation of low hypapophyses, and posterior and transverse 

 position of parapophyses. 



AMrHICOELIA. 



HYPOSAURUS, Owen. 

 Journ. Geol. Soc, London, V., 383. 



This genus is as yet the only known representative on this continent of the Amphi- 

 coelian Crocodiles. It belongs, says Owen, to the Teleosauridae, from which the great 

 size of the parapophysis distinguishes it. Its remains are quite abundant in the New 

 Jersey cretaceous ; stratigraphically its position is the latest of its family. Thoraco- 

 saurus being the earliest of the Procoelian Crocodilia, the interesting spectacle is pre- 

 sented of the coexistence in America in large numbers, of two types which, in the old 

 world, are separated by the whole period between the Jurassic and Tertiary. 



As might be supposed then, there is some approximation in structure between these 

 two extreme genera of their series. The hypapophyses of the cervical vertebra in Thor- 

 acosaurus are of the Teleosauroid type. Both are. alike slender-nosed genera, as I have 

 been able to ascertain for the first time for some of them. 



As a Teleosaurian reptile the bassioccipital does not present the vertical position usual 

 among the Procoeli, but is horizontal. The sphenoid is also more horizontal in its expo- 

 sure, and much wider, and with a straight anterior margin, not incised to accommodate 

 the posterior nares. The frontal bone is marked with longitudinal shallow grooves. 



The teeth of Hyposaurus are more compressed than in the last genus described, some 

 of them are from the shortening of the crown almost triangular in outline, but most are' 

 elongate ; the enamel is thrown into a Tew fine continuous ridges. 



The cervicals may be distinguished from those of the other gavials of New Jersey, in 

 addition to the form of the articular faces, by the earlier appearance of a strong keel-like 

 hypapophysis, that is, on the fourth of the series ; at first it is most prominent at the 

 anterior end. 



HYPOSAURUS ROGERSII, Oicen. 



Loc. Cit. Leidy, Cretaceous Reptile 3ST. Am., p. 18, Tab. Ill, 4-21. 



Vertebra. — The neural spines of the cervical vertebrae are acuminate, of considerable — finally, of great — height, 

 the anterior standing transversely on the neural arch, the median subtetragonal, the posterior, as usual, 

 longitudinal in section. In an anterior cervical vertebra, length 2 in., the spine is 2 in. 10 1. above the ceiling of 

 the arch, and is acute ; it receives a strong lateral wing from each posterior zygapophysis, which does not disappear 

 till near the tip. These enclose a deep groove on each side behind, with a strictly perpendicular posterior median 



