72 REPORT — 1841. 



vertebra expands in a greater degree to form the snbconcave articular sur- 

 faces than in other biconcave vertebrse of the same length ; and both in this 

 character, in its smooth surface, and circular transverse contour at the lower 

 part, the Goniopholis resembles the Streptospondylus more than it does the 

 Teleosaums. 



The medullary canal, at the middle of these vertebrae, presents in trans- 

 verse section the form of an inverted triangle, the apex sinking into the body 

 of the vertebra. The transverse processes of the lumbar and anterior caudal 

 vertebrae are long, straight, and comparatively slender ; those of the sacral 

 vertebrae arc relatively thicker, and the spaces inclosed by their expanded ex- 

 tremities are smaller than in either the Teleosaurs or true Crocodiles. The 

 antero-posterior extent of the two sacral vertebrae is three inches two lines. 



The ilium is broader than in the existing Crocodilians ; the bifurcation of 

 the proximal end of the ischium is more marked, and the iliac branch is more 

 regularly rounded ; the pubic branch is longer, more slender, and its articular 

 end is more regularly convex ; the distal or lower part of the ischium expands 

 into a relatively broader plate. This character is still more conspicuous in 

 the pubis, M'hich equals the ischium in breadth, and begins to expand much 

 nearer the proximal extremity than in the existing Crocodiles. In these 

 modifications of the pelvis, as well as in the biconcave structure of the ver- 

 tebra, the Crocodilian of the Purbeck limestone approaches nearer to the 

 characters of the Enaliosaurs ; and we may infer that its habits were more 

 decidedly marine than are those of existing Crocodilians. The caudal verte- 

 brae were provided Avith long, narrow, unanchylosed chevron bones. 



The portion of the lower jaw preserved belongs to that part of the left ramus 

 included between the articular extremity, which is broken off, and the com- 

 mencement of the dental series ; it measures one foot six inches in length, and 

 five inches in greatest depth. In these proi^ortions, and the curve of the lower 

 margin, it deviates from the ancient Teleosaurs and Steneosaurs, and resembles 

 the modern Crocodiles ; and although not quite equalling these in the robust 

 proportions of the jaws, yet it much exceeds in this respect the Crocodilians 

 with more slender teetli. What the i-eal length and form of the jaws may 

 have been, and how nearly they may have approached the Gavial type, there 

 is not at present means to determine. Sufficient, however, has been pointed 

 out from the remains which are at present discovered, to show that the Swanage 

 Crocodilian differs from the existing subgenera of Crocodilians in a greater 

 degree than these do from one another; that in the form of its vertebrae and 

 the structure of the dermal armour, it is much more nearly allied to the 

 Teleosauri and other Crocodilian genera of the biconcave vertebral system ; 

 and that, in this ancient and extinct group of Crocodilians, it typifies the 

 Alligator family of the Crocodilians of the ball-and-socket vertebral sj'stem. 



I propose to name the subgenus indicated by the known remains of the 

 Swanage Crocodile, Goniopholis, in reference to the rectangular form, size, 

 number, and firm junction of the osseous scutes (cjioXiSes), with the specific 

 name of " crassidens." 



In a collection of fossil Saurian remains from the Hastings beds in the 

 possession of Gilpin Gorst, Esq., F.G.S., is the base of the tooth of the Go- 

 niopholis crassidens, eight lines in diameter. 



Remains of Crocodilians are stated by Dr. Mantell to have been found, 

 though very rarely, in the lower chalk, and in the grey chalk at Dover*. 



Teleosaurus. 



The family of extinct Crocodilians, which next remains to be noticed, is 



• Illustrations of the Geology of Sussex, 4to, 1827, p. 64. 



