GEOLOGICAL SURVEY OF THE TERRITORIES. 421 



giving a total of near ten feet for the length of this fish. It was dis- 

 covered at a point on the bank of the Solomon's or Nepaholla Biver, in 

 Kansas, 160 miles from its point of junction with the Kansas Eiver. 



SATJRODON, (HAYS.) 



(Transac. Amer. Philos. Soc, 1830, 476.) 



SATJRODON LEANTJS, (HAYS.) 



(Loc cit. Tab. xvi. Leidy, Trans. Am. Philos. Soc, 1856.) 

 From the cretaceous green sand of New Jersey. 



ICHTHYODECTES, (COPE.) 



(Proceed. Amer. Philos. Soc., November, 1870.) 



In this genus the teeth are subcylindric and slender, without cutting 

 edges. The inner margins of the maxillary and dentary bone exhibit 

 no dental foramina, which are in Sauroceplialus and tSaurodon of large 

 size. 



ICHTHYODECTES CTENODON, (COPE.) 

 (Loc. cit.) 



This species is established on one complete maxillary bone, and three- 

 fourths of the other, a large part of the dentary bone, with the entire 

 dental series; numerous portions of cranial bones, with thirteen verte- 

 brae. These, according to Professor Mudge, were found together, and 

 to all appearance belong to the same animal. 



The dental characters differ from those of Sanroccphalus, as above 

 pointed out, and in this species more than in 8. leanus. The crowns of 

 the teeth are more exserted and slender. The inner face of the crown is 

 more convex than the outer; but there is no angle separating the two 

 aspects. The apex is moderately acute, and directed a little inward, 

 owing to a slight convexity of the external face. Enamel smooth. The 

 alveoli are very close together, and are probably only separated in their 

 deeper portions. There are forty- two teeth and alveoli in the maxillary 

 bone. The palatine condyle is low, and its anterior border falls opposite 

 to the last tooth, or the indented surface which was occupied by the pre- 

 maxillary bone. The more proximal part of the maxillary curves inward 

 and backward behind the position of the premaxillary more than in 8. 

 prognathus. The maxillary is a rather thin and narrow bone, with a 

 broad, obtuse and thinned extremity. Its superior margin is marked with 

 one or more acute ridges, which look as though it had a contact with a 

 large preorbital bone. Two fractured bones with an elongate reniform 

 condyle on a wide peduncle, look like the articular extremity of an oper- 

 culum, which view is confirmed by their application to some flat, coarsely- 

 rugose bones which resemble parts of the latter. 



The dentary bone is remarkable for its straightness and laminar char- 

 acter, and for the depth of the symphysis. The length of the latter is 

 preserved, while posteriorly to it the lower margin of the dentary is 

 broken away. The alveolar margin is slightly concave, and unites with 

 the symphyseal at an angle of 65°. There are twenty-seven teeth and 

 alveolae, which grow a little larger to the posterior extremity of the 

 series ; anteriorly the alveoli are confluent externally, but posteriorly the 

 septa are frequently complete, though thin. In neither this bone nor the 

 maxillary are to be found the formina along the bases of the teeth, char- 



