W. Bavies — On Scmrocephalus. 259 



latter element was correctly determined, but the premaxillary was 

 called maxillary in my description." Having obtained another 

 specimen from Kansas, he continues, "From this and other specimens 

 I discover that the anterior portion of the skull, probably the ethmoid 

 bone, is produced in a long beak, in general form similar to the 

 sword-like snout of the Sword-fishes of modern seas." The pro- 

 longation of the ethmoid into a long snout is an important discovery, 

 as it clears the difficulty in regard to the bones previously referred 

 to the premaxillaries. He continues, " The specimen above mentioned 

 includes also the maxillary bones, so that their true character is now 

 clear. A remarkable feature of the genus is displayed in the man- 

 dibles. Each of these is compound in the region usually composed 

 of the simple dentary bone. It there consists of three parallel 

 elements, an internal and an external embracing a median element. 

 The inner bears a band of teeth en hrosse on its inner and superior 

 aspect, and the external a few teeth of similar character, on its 

 superior edge. The large lancet-shaped teeth are borne by the 

 middle element, excepting some of the largest near the symphysis. 

 Two of these on the inner side of the ramus originate in the internal 

 bone." 



The mandible figured by Dixon has but two parallel elements in 

 each ramus, and bears no inner " band of teeth en hrosse on its inner 

 and superior aspect ;" proving that the number of the elements in 

 the region of the dentary bone is only of specific and not of generic 

 value. Other points of specific diiferences in the respective mandibles 

 I have previously mentioned. Prof. Cope further states that, •' ante- 

 rior to the premaxillary bones, on the inferior aspect of the ? ethmoid, 

 is situated a pair of large, compressed, double-edged teeth, whose 

 alveoli are close together. Only one of these teeth is in functional 

 service at a time." Here again, supposing this to prove a constant 

 character in the American fossils, the species of the two countries are 

 not in harmony; for in Mr. Dixon's collection is a proximal portion 

 of a rostrum, referred by him to the upper jaw, in which both teeth 

 are preserved intact; they are nearly equal in size and fully developed 

 (Plate VIII. Fig. 3) ; and in another specimen in the British Museum, 

 although the crowns are broken, and one tooth is larger than the 

 other, yet they demonstrate clearly that they were both sufficiently 

 projected beyond their respective alveoli as to have been in func- 

 tional service together. In other imperfect examples in the same 

 collection, the fangs show that the lost crowns of the teeth must 

 have been well if not equally developed. And in all, one tooth, the 

 largest, is slightly in advance of the other. The rostra are hollow for 

 a large portion of their length. 



Prof. Cope, to whom we are largely indebted for his original 

 investigations on the Cretaceous fossil fishes, refers Erisichthe to his 

 family Saurodontidce, in which group of fishes, sjjecies of most of 

 the genera are to be met with in the Cretaceous formations of 

 England. 



iSaurocevTialus lanciformis will, therefore, excepting as a synonym, 

 have to be excluded from the catalogue of British fossils, and the 



