EATJNA OP THE GOSAT7 FORMATION. 



673 



out : but there were not fewer than fifteen ; and as the alveolar 

 groove is carried back and becomes very shallow beyond this 

 point, it is possible there may have been five teeth more, of small 

 size, in the hinder part of the jaw, making a total of twenty. The 

 teeth are largest in the middle of the jaw ; but only the tenth on 

 the right side has the crown preserved in situ. The crown is 8 mil- 

 lion, high, and nearly 6 millim. wide at its base. It is trian- 

 gular in lateral outline, is curved inwards and directed upwards, 

 inwards, and backwards. Its base is rather less than 3 millim. 

 thick. Each surface is convex, terminating in a sharp cutting-edge, 

 which is very finely serrated along the margin. In front and be- 

 hind there is a constriction, so as to separate the sides of the crown 

 from the elliptical fang ; but this constriction is not appreciable on 

 the interior or the exterior aspect of the tooth. This form of tooth 

 is entirely Dinosaurian. Four teeth have been found separately 

 which show the same character. Two of these are crowns broken 

 off directly from the fang, and show the constricted oval base of the 

 crown where the lateral ridges become pinched in. These teeth 

 are sharply pointed, and have the surface smooth to the naked eye. 

 There are also two teeth which have the same general form, except 

 that the crown is broader and shorter ; and, owing to this circum- 

 stance, the serrations, which are transverse to the cutting-edge, 

 have an appearance of being directed obliquely upward. These, 

 however, are probably succession al teeth, it may be from another 

 part of the jaw, or from the upper jaw. A certain amount of varia- 

 tion is obvious, because the fang of the eleventh tooth on the left 

 side shows that the base of the crown was marked with blunt 

 parallel ridges. 



There is a fragment of the anterior end of a right dentary bone 

 from which the opercular element has come away, and which clearly 

 belongs to the same genus. It may indicate another and smaller 

 species, since the rami appear to diverge more rapidly, to have con- 

 tained more numerous teeth, with smaller and more circular fangs, 

 to want the anterior elevation of the jaw in its presymphysial region, 

 to be devoid of the ridge between the base of the jaw and the side, 

 and to have the side convexly inflated instead of flattened, especially 

 external to the alveolar margin. The ornament also ajjpears to be 

 slightly different ; but as no teeth are preserved I have not thought 

 it necessary to give a name to this fragment. The length of the 

 dentary symphysis is 1 J centimetre, and the length of the fragment 

 4| centimetres. The corresponding length of the dentary symphysis 

 in the larger specimen exceeds 2| centimetres. 



The fragment of upper jaw briefly described by Biinzel, p. 6, pi. i. 

 figs. 3-5, I have, as already mentioned, identified with the lower 

 jaw of the large species just described. Notwithstanding the circum- 

 stance that Biinzel remarks on its close resemblance to existing 

 crocodiles, he places the nasal aperture immediately in front of the 

 orbit, which alone would suffice to show that the type differed from 

 crocodiles fundamentally. In fact, the perforation of orbit and 

 nares in the maxillary bone would be a modification of old-fashioned 



Q.J.G.S. No. 148. 2y 



