430 BRITISH FOSSIL REPTILES. 



from the ancient Teleosaurs and Steneosaurs, and resembles the modern Crocodiles ; 

 and although not quite equalling these in the robust proportions of the jaw, yet it 

 much exceeds in this respect the Crocodilians with more slender teeth. 



Portions of the skeleton of a GonwphoUs, kindly submitted to my examination by 

 G. B. Holmes, Esq., of Horsham, by whom it was discovered in a Wealden stratum 

 at Cuckfield, Sussex, shows the symphysis of the lower jaw (Pi. 12, fig. 4) to have 

 been as long in the Crocodilus Spenceri (' Crocodilia,' PI. 2, fig. 2), a transitional 

 form between the modern Crocodile and Gavial. The fore part of the premaxillaries 

 (PI. 1 1, figs. 1 and 2) shows a semicircular anterior contour, and a single subcircular 

 nostril, placed rather nearer the termination of the muzzle than in existing Crocodiles, 

 but yet above, not terminal, as Teleosaurus, not subterminal, as in Steneosaurus. 

 Tiiere is not enough of the bone preserved to show whether there was a constriction 

 of the upper jaw behind the nostril, as in the Gavial. The incisive foramen is not 

 immediately beneath the nostril, as in the modern and tertiary Crocodiles (comp. 

 PI. 1, c, with Pi. 11, fig. 2). The outer surface of the premaxillaries is convex, rather 

 irregular, with vascular foramina and wrinkled impressions. The margins of the 

 symphysis are a little produced. There are four alveoli in each premaxillary, as far 

 as the bone is preserved ; they are proportionally larger, more numerous, and closer 

 together than in the corresponding part of the Streptospondi/luii or Steneosaurus brevi- 

 rostrus {' Ossem. Fossiles,' 4to, t. v., pt. ii, pi. x, fig. 6). The first and smallest socket 

 is in contact with the second, which is the largest; the intervals increased beyond 

 this socket (PL 11, fig. 2). The palatal surface shows a pair of large and deep 

 approximate fossae, and a second pair of smaller fossae for lodging the crowns of the 

 anterior teeth of the lower jaw. This is very slightly expanded at its anterior end, 

 where the larger (third and fourth) tusks are implanted. The fragments of the 

 mandible indicate a symphysis of, at least, eight inches in length ; at the anterior 

 three inches the rami interlock by strong, radiating ridges and grooves (PI. 12, fig. 1). 



The teeth are well preserved in parts of these fossil jaws the cylindrical fang 

 is invested by smooth cement ; the coronal ridges begin at the basal line of the 

 enamel, and proceed nearly parallel to the apex of the cone. In a tootli with a 

 crown one inch long and half an inch across the base four ridges are included in a 

 space one line broad ; a few of tlie ridges are interrupted to preserve the parallelism 

 of the rest. Towards the apex a number of shorter and finer ridges are present on 

 each side of the two chief ridges, to which they obliquely converge. At the extreme 

 apex of an unworn tooth the ordinary ridges terminate in fine, slightly wavy lines, 

 forming a subreticulate surface. 



In the Jurassic Crocodilian, called Madrimosaurus by V. Meyer, the coronal ridges 

 of the teeth are more numerous, are smaller at the base of the enamel, and more of 

 the ridges are interrupted than in Goniopholis ; the entire tooth also seems to be 

 shorter and thicker. 



