KIMMERIDGIAN CROCODILES. 149 



tlie premaxillary teeth the third is rather larger than the rest ; the maxillary series 

 begins by one somewhat smaller, the rest are of larger size, and maintain it to the 

 thirteenth, the remaining two slightly decreasing ; but a general uniformity 

 prevails throughout the series. The base of the ninth tooth has a diameter of 

 1 inch, 2 lines, with a circular transverse section; that of the second (pre- 

 maxillary) tooth gives 10 lines in the same direction. 



The upper jaw, with a basal breadth of 7 inches, gradually and uninterruptedly 

 narrows to 2^ inches across the foremost pair of sockets. The palatal interspace 

 between these sockets does not exceed that which separates the socket of the first 

 from that of the second tooth. This interspace seems not to have exceeded 4 

 lines at the alveolar outlet ; the interspaces of the maxillary alveoli are so much 

 less, that most of the teeth of the same series between the two extremes must have 

 been nearly, if not quite, in contact basally. The breadth of the palate between 

 the third pair of teeth is 2 inches ; between the last pair it is 8 inches. The mid- 

 line of the mouth-roof is slightly produced. 



Portions of the broken off crowns of the teeth show the two-ridged Crocodilian 

 character, with a smooth intervening enamel. Two of these detached crowns 

 (ib., fig. 4) seem to indicate the extent to which the upper and lower teeth over- 

 lapped in the closed mouth; of these the best preserved gives a length of 4|- 

 inches. A transverse fracture of a tooth-crown, where its diameter had fallen to 

 7 lines, shows a pulp-cavity diminished to 3 lines. 



The upper aperture of the temporal fossa is six and a half inches in transverse, 

 and seven inches in fore-and-aft, diameters. The upper (post-fronto-mastoid) 

 boundary curves outwardly, with a thick convex surface. The mandibular muscle, 

 which it included, had a size conformably with the close-set series of large teeth, 

 which it worked. 



The frontal bones, ii, converge to a point, ten inches distant from the 

 premaxillary apex of the skull. The nasal bones, is, gradually narrow to a point 

 penetrating the hind border of the nostril, n. This opening is ovoid, three inches 

 and a half in length, three inches in greatest breadth. The premaxillaries meet 

 and join an inch and a half anterior to the horizontal nostril.^ 



The transition to tertiary and existing Crocodiles is manifested by the propor- 

 tions of the skull and of the teeth ; but these, in the degi'ee of general equality of 

 size, are gavial-like, while in relative size and paucity of number they show the 

 Crocodilian character in excess. 



There is no trace of an alveolar pit in the upper jaw for the reception of a 

 lower canine, as in the Alligators, nor of any lateral notch for such a tooth as in 



1 " Les intermasillaires, a, a (figs. 1, 2, 3), entourent les narines externes, excepte un endroit fort 

 etroit ou la pointe des os nasaux, Tc, k, se place entre eux." " Determination des OS de la tfite dans 

 les Crocodiles proprement dits." ' Ossem. Fossiles,' v, pt. ii, pp. C9, 71. 



