CHAKACTJillS OF HECENT CROCODILIA. 9 



maxilla. The suture then turns abruptly forwards until it reaches 

 the level of the anterior margin of the alveolus of the sixth tooth,' 

 when it bends suddenly inwards to meet its fellow. The whole 

 suture, therefore, has the form of a W. The vomers are com- 

 pletely hidden. 



The posterior nares look downwards and backwards ; their aper- 

 ture is, from the incompleteness of the septum, single, and has a 

 transversely elongated erescentic form. It measures 1^ inch in 

 width by fths antero-posteriorly. The basi-sphenoid is seen for 

 about -ith of an inch on the base of the skull behind it, bounding 

 the sides of the eustachian tube. The dental formula is i^zl^. 



15—15 



Tlie fourth and tenth teeth are largest in the upper jaw, the first 

 and fourth in the lower. The eight posterior teeth on each side 

 in the upper jaw, and the five posterior in the lower, have a 

 marked constriction between the short crown and the fang of the 

 tooth. There are deep interdental pits for the reception of the 

 mandibular teeth between the third and fourth, and fourth and 

 fifth teeth above, and between the succeeding teeth from tlie 

 sixth to the thirteenth. 



The hyoidean cornua are very strong curved bones, the chord of 

 whose arc measures 3^ inches. They are concave inwards, convex 

 outwards, concave posteriorly, convex anteriorly ; they are flat- 

 tened from side to side below, but they end above in subcylin- 

 drical styloid extremities. 



In the ninth vertebra the neurocentral suture passes just above 

 the base of the parapophysis ; it traverses the parapophysis in the 

 tenth and eleventh vertebrae, while in the twelfth the parapophysis 

 suddenly rises to the root of the diapophysis, and the suture lies far 

 below it. The centra of the dorsal vertebrae, as far as the thirteenth 

 inclusive, have hypapophyses. The diapophyses of the ninth ver- 

 tebra pass almost horizontally outwards, but are a good deal in- 

 clined backwards. In the succeeding vertebrae up to the fourteenth 

 or fifteenth, the diapophyses are, in addition, inclined upwards, the 

 upward inclination being most marked in the tenth, eleventh and 

 twelfth vertebrae. Prom the fifteenth vertebra onwards, the 

 transverse processes pass almost directly outwards, without either 

 upward or backward incliuation. The span of the transverse pro- 

 cesses is greatest in the eighteenth and nineteenth vertebrae, in 

 which the distance between the extremities of these processes is 

 7-|- inches, a length about equal to that of the longest vertebral rib. 



The rib of tlie ninth vertebra is terminated by a single long and 

 slender semicartilaginous process which does not unite with the 



