650 BRITISH FOSSIL REPTILES. 



its connections with the frontal (n), post-frontal (12), and pre-frontal (n) in the left 

 orbit (0); but has become slightly detached in the right orbit (o'). The nasal bones 

 (15) terminate in a point distant from the external noscril by rather more than the 

 diameter of that aperture, which accordingly is single and exclusively bounded by the 

 preniaxillaries. In this character Crocodilius cataphractus and Croc, intermedius 

 resemble Nannosuchus ; but the upper jaw is longer and more slender in proportion in 

 both these existing Crocodiles than in the Purbeck species ; in both, also, the upper 

 temporal apertures are relatively smaller than in Nannosuchua. 



In the character of the nasal bones and conformation of the external nostril Nanno- 

 suchus resembles GoniophoHs (PI. 40), but the supra-temporal apertures are more oblong and 

 the maxillaries are not so out-swollen as they approach the premaxillaries. The facial 

 part of the skull, from the front border of the orbit forwards, equals the extent of the 

 skull from the same part to the occiput in Nannosuchus ; in Goniopholis the facial part 

 of the skull, so defined, is one third longer than the extent behind. The mutilated state 

 of the unique skull of Petrosuchus prevents a similar comparison being made. 



The sculpturing of the upper surfaces of the exposed parts of the skull in 

 Nannosuchus presents the common Crocodilian character of minute subcircular pits, 

 leaving a reticulate disposition of the intervening bone. 



Genus — Theriosuchus,^ Owen. 

 Species — Theriosuchus pusillus, Ow. Crocodilia, Plate 44, figs. 3—18 ; Plate 45. 



This Crocodile, somewhat smaller in size than the preceding species, approaches 

 nearer to the type of the broad-faced Alligators in the proportion of the antorbital part of 

 the skull. 



The dentition is more modified than in any other known Crocodile, recent or extinct, 

 and approaches that which characterises the Theriodont order of Triassic Reptilia. 



The premaxillary teeth are five in number in each bone; the three middle ones 

 subequal, the first and fifth smaller. The maxillary teeth are divisible into laniaries and 

 carnassials or trenchant molars. The first maxillary tooth is small (PI. 44, fig. 5) ; 

 the second and third gain quickly in size, the latter (a) assuming the character of a 

 canine ; the fourth tooth {b) is a still larger canine ; the fifth (c) and sixth [d) decrease in 

 size somewhat suddenly, but in length rather than brcadtli of crown, and terminate 

 the series projecting from the convex part of the alveolar border of the maxillary. The 

 tooth c ox d may be said to terminate the laniary series. Beyond d the teeth lose 

 length and slightly gain in breadth ; the crown assumes a triangular, laterally corn- 

 er, dtjpwv, wild beast ; a-uv)(^oi, crocodile. 



