1859.] HUK.V REPTILIAN FOSSILS. 59 



The occipital plane is singularly inclined from below upward and 

 forward, and that of the occipital foramen (fig. 3 /) partakes of the 

 same inclination, the condyle (figs. 2 & 3 <j) being much produced 

 behind and beyond the upper border of the foramen. The shape of 

 the occipital surface, which is completely or continuously ossified, is 

 triangular, bounded laterally by a pair of strongly developed sharp 

 ridges, converging upward and forming the boundary between the 

 occipital (2, 3) and temporal (t) fossae. The occipital surface may be 

 called a "fossa'' from its concavity ; but the surface is undulated by a 

 median and two lateral slight convexities along lines radiating from 

 the foramen magnum. 



The parietal crest (fig. 3 7), advancing from the angular summit 

 of the occipital ridge, bifurcates to surround an elliptical " foramen 

 parietale;" and the divisions thence gradually diverge to the post- 

 frontal (12). The tympanic (2a) is a broad deep plate of bone, convex 

 outwardly ; it extends outward and forward from the lower part of 

 the occipital ridge, formed by the mastoid (h) and paroccipital (-1). 



The zygomatic arch is continued forward from tbe tympanic 

 (fig. 1 2s), a little decreasing in depth, to the postorbital boundary (20). 

 The temporal fossa (fig. 3 t) is very wide, and is of a rhomboidal 

 figure, the antero-lateral boundary being parallel with the occipital 

 ridge, and the postero-lateral boundary being parallel with the in- 

 ternal or cranial boundary. The long diameter of the fossa is 1 inch 

 3 lines ; its short diameter is 1 inch ; from the front to the hind 

 angle the fossa measures 1 inch 6 lines ; the breadth of the cranium 

 between the fossa; is 6 lines. 



The orbits are of a subtriangular form, with the corners rounded 

 off: their aspect is more upward than outward : their long diameter 

 is 6 lines : the breadth of the upper interorbital space is 9 lines. 

 The suture between the frontals and nasals is parallel with the fore 

 part of the orbits. The post- (12) and pre- (14) frontals unite above 

 the orbit, and contribute a narrow tract to each side of the interor- 

 bital space: this space is fiat. The nasals are flat: the rounded 

 angles by which the upper surface passes into the vertical side-sur- 

 face of tin- facial part of the skull are formed by the maxillaries. 

 The nostril (figs. 1 & - /')• is single, terminal, ami vertical; it is 

 bounded laterally by short premaxillaries. 



The most interesting peculiarity in the skull is the well-marked 

 definition from the other teeth, by ;i contrasted superiority of sise, 



of an upper and lower canine tooth on each side, having the same 



position in the skull ami relative position to e.idi other as in the 

 Carnivorous mammals. Ill no other Saurian are incisors so divided 

 from molars by a single canine; in none is such definition of the 



three kinds of teeth so plain and unequivocal. 



The premazillaries contain each four equal-sized teeth with simple 

 conical crowns. 2 line-- in Length, sloping a little forward from the 



vertical position, and passing ill front of the lower im 080X8 w hen th. 

 mouth ifl shut. The eight lower incisors are narrower, hut ha\e 



ahout the same length of 1 pot n. Both upper and Lower im isors are 

 arranged in contact, or 1 lost order, as in Mammals. 



