W. Davies — On Saurocephalus. 257 



of the West."^ They consist of a maxillary, supposed premaxillaries, 

 and the anterior portion of a left mandible; and so alike are the 

 maxillary and mandible to the specimens figured by Dixon that 

 there could be no doubt as to their being generically the same if we 

 could assume that Cope had erroneously determined the bones he 

 refers to the premaxillaries ; but if he is right, they cannot be cor- 

 related, for in the American species the premaxilla^ are not prolonged 

 into a bony rostrum, a feature not mentioned by him as characteristic 

 of this, or even of any other species described in the above- 

 mentioned work. Yet it would seem as though he had a doubt as 

 to the correctness of his interpretation of these bones, for he does 

 not refer to them in his diagnosis of the genus nor in his description 

 of the species. The maxillary bones, he states, " are sub-ti'iangular 

 in form, and support three or four large lancet-shaped teeth at the 

 middle of their length. There are no teeth beyond them ; but, on 

 the deeper side, there are several small lancet-shaped teeth." ^ 



The maxillarj' figured in Dixon, but of which no description is 

 given, is also sub-triangular in form, but much deeper in proportion 

 to its length than the ErisicTiihe nitida, Cope ; the surface having an 

 iri'effular ruo-ose ornamentation. It shows a continuous series of 

 seven lanciform and equidistant teeth, increasing in size from the 

 anterior tooth to the fourth ; this, and the posterior teeth, appear 

 from the alveoli to have been of uniform size. Three teeth are in 

 situ, viz. the first, or anterior, the fourth and sixth, the others being 

 represented by the alveoli alone. More or less deeply seated in each 

 of these are the apices of successional teeth. It also differs from 

 E. nitida, insomuch that it has no outer row of small lancet-shaped 

 teeth. The anterior termination of the bone is wanting; it measures 

 in length three and a half inches, and one inch and a half at the 

 deepest part between the sixth and seventli alveoli, the pre- 

 maxillary sutural margin being entire. 



The anterior portions of the mandibiilar rami, having regard to 

 specific dijfferences, are so alike in the respective drawings of Cope 

 and Dixon, that they might be assigned without a doubt to the same 

 genus, were it not for the other fragments which are referred to it by 

 Cope. His description of this bone is as follows : — 



" The teeth on the greater part of the dentary are intermediate in 

 size between the large and small ones of the maxillaries ; they stand 

 on the outer edge of a broad horizontal alveolar plane. There are 

 three large teeth in a series at the end of the dentary on the outer 

 side ; they have been lost, but their bases, are broader ovals than 

 those of the maxillary bone. On the middle line of this part of the 

 dentary is a close series of small compressed teeth with striate enamel, 

 standing on a ridge of the bone ; they leave the last large tooth to 

 the outer side, while on the inner side stand two or three lancet- 

 shaped tusks of a short row further back." — op. cit., p. 218. 



The characters of the specimen from Kent are thus defined in 

 Dixon's work : — 



1 Eeport of the United States Geological Survey of the Territories, vol. ii. 1875. 



2 op. cit. p. 218. 



DECADE II. VOL. V. — NO. VI. 17 



