10 FOSSIL REPTILIA OF THE 



p. 128), — an evil which, if the " names " do not represent " generic distinctions," cannot 

 be laid to the charge of the " Palaeontologist." 



At least, the " small fragments of the fossil skeleton " (ib., p. 128) on which the 

 genus Goniopholis was originally founded have subsequently been proved, by acquisition 

 of other parts, to have indicated accurately that well-marked and interesting addition 

 to the recorded modifications of the Crocodilian type. Those of the vertebral and 

 cranial structures have, indeed, proved to be not only of generic, but of family value. 



Genus — Petrosuchus, Owen} 

 Species — Petrosuchus levidens. Plate VI. 



This genus and species of Crocodile is founded on the portion of skull and mandible, 

 figured in Plate VI. The skull is imbedded in the same limestone of the Middle 

 Purbecks, now quarried at Swanage. It was discovered in a block with the upper 

 surface (ib., fig. 1) exposed. This surface is partially weathered, but shows here and 

 there a faintly wrinkled natural sculpturing. The upper temporal apertures are larger 

 than the orbits. In front of these the skull contracts more rapidly than in Goniopholis, 

 and presents, as far as it is preserved, a slender form of face approaching to the propor- 

 tions of that in the modern Crocodilus cataphractus? and in the Tertiary Crocodilus 

 champsoides ; 3 but the more rapid contraction in front of the orbits is gavial-like, and there 

 are other characters indicative of a nearer affinity than in Goniopholis to the Teleosaurian 

 group. This affinity .is decisively marked by the larger relative size and more advanced 

 position of the palatonaris (ib., fig. 2, n), into the formation of which the diverging hind 

 ends of the palatines (ib., fig. 2, 20) enter in a larger proportion than in Goniopholis. 

 The basisphenoid (ib., ib., 5) is more produced, and the pterygoid (ib., ib., 24) contracts 

 a more extensive sutural union therewith. Each palatine bone (ib., ib., 20), where they 

 diverge at the palatonaris, shows a protuberance on its under surface. The Eustachian 

 outlet is seen at «. 



The portion of the left mandibular ramus (PI. VI, fig. 3) includes the dentary 

 element (32), nine inches in length, with portions of the angular (30) andsurangular (29) ; 

 that of the angular including six inches of its extent. Of this element two inches 

 extend forward in advance of the hindmost point of the dentary ; and, guided by 

 the proportions of the Crocodilus champsoides, I estimate the total length of the 



1 Gr. irerpos, rock, and lov-^vs, an Egyptian name of the Crocodile. 



2 Cuvier, 'Ossem. Foss.,' 4to, torn, v, part ii, pi. v, figs. 1 and 2; Gray, 'Trans. Zool. Soc.,' vol. vi, 

 pi. xxxii, fig. 2. 



3 Pal. vol. for the year 1849, ' Fossil Reptilia of the London Clay,' t. iii. 



