2 S. W. WILLISTON 



Gavialis, where it remains to the present time, though doubtless 

 belonging in one or another of the tomistomid genera which have 

 been described from the New Jersey deposits, if not really a Hypo- 

 saurus, as Cope first believed. 



Leidy founded the genus and species Thoracosaurus grandis upon 

 dermal plates from the same horizon. ' He later assigned to the 

 same species,^ under the name Thoracosaurus neocesariensis De 

 Kay,3 an excellent skull, unassociated with other bones. I have read 

 attentively Leidy's descriptions and remarks, as also those of Cope, 

 concerning this and other specimens referable to this species, and 

 nowhere do I find a positive collocation of the type with procoelous 

 vertebrae, though Leidy assigned to the species the procoelous verte- 

 brae previously described by Owen as Crocodilus basifissusJ It is 

 probable, however, that Thoracosaurus is really a procoelian croco- 

 dile, since Holops Cope, a nearly allied, if not identical, genus, has 

 been definitely associated with procoelous vertebras. ^ Furthermore, 

 Koken referred to the same genus, ^ though with some hesitancy, a 

 skull from the Maastrichtian of northern Germany, which he identi- 

 fied specifically with Thoracosaurus niacrorhynchus (Blaineville) 

 Leidy,'' originally described from the Lower Eocene of Germany. 

 This geographical distribution is not at all remarkable, since we 

 know that the genus Mosasaurus has a like distribution in the 

 Maastrichtian of Belgium and the Cretaceous of New Jersey, as also 

 the Pierre of the interior. We may, therefore, accept both Thoraco- 

 saurus and Holops as procoelian crocodiles, though further informa- 

 tion as to the skeletal structure of each is highly desirable. 



As to the third genus of crocodiles reputed to be Drocoelian from 

 the Cretaceous of New Jersey, Bottosaurus Agassiz,^ I do not think 



1 Leidy, Proceedings of the Academy of Natural Sciences, Philadelphia, Vol. VI 

 (1852), p. 35. 



2 Leidy, Cretaceous Reptiles (1865), p. 5, Plates J-III. 



3 DeKay, Zoology of New York, Part III, p. 28, Plate XXII, Fig. 9 {Gavialis). 

 4 Owen, Quarterly Journal of the Geological Society, Vol. V (1849), P- S^^i Plate 



X, Figs. I, 2. 



sCope, Extinct Batrachia, etc. (1865), p. 69, Plate I, Fig. 13. 



•5 Koken, Zeitschrift der Deutschen geologischen Gesellschaft, 1888, p. 754. 



7 Leidy, Cretaceous Reptiles (1865), p. 8. 



^ Agassiz, Proceedings of the Academy of Natural Sciences, Philadelphia, Vol. IV 

 (1849), P- 169. 



