GEOLOGICAL SURVEY OF THE TERRITORIES. G37 



articular surfaces for the neurapopbyses are 8-shaped, the area confluent. 

 A marked peculiarity is seen iu the dentary bone. It is much curved in 

 the vertical plane as \A'ell as iu the horizontal, and must have inclosed 

 a wide mouth. The groove is median, and the inferior and supe^-ior 

 surfiices reach it by a nearly equal slope. The former leaves the alveoli 

 without horizontal border, thongh the latter themselves open on a hori- 

 zontal plane. There are four and a fraction in .010^. 



3Ieasnrements. 



M. 



Dept'n of ramus at middle 0, 013 



Thickness of ramus at middle 006 



Length posterior dorsal vertt?bra 00(5 



Depth posterior dorsal vertebra §12 



Width posterior dorsal vertebra 013 



From Upper Green Eiver. 



PIIAREODON, Leidy. 



Proceedings Academy Nat. Sciences Phila., 1873, 



This genus belongs to the order of Nematognatlii, as I discovered by 

 various specimens in my possession. 



The usual modification of the anterior vertebrse exists in this genus. 

 The mass is carinate below, and Hears two longitudinal cavities sepa- 

 rated by a low partition above. The palatine bones support a mass of 

 teeth, there being one external series of large ones rather abruptly 

 pointed, and several series of small ones of little elevation, whose size 

 diminishes inward. The dentary bone is narrow and deep and sup- 

 ports a single series of closely placed slender teeth, which together form 

 a comb. •• The bases of these teeth are rugose-striate, and the apices 

 abruptly acuminate. 



The vertebrtB are short, and with reticulate ridges on the sides. 

 There is a pit on each side, and there are two pits on each of the sides 

 above and below. The vertebra appears to be a caudal, and the connate 

 hoemapophysis issues from between the lateral and inferior pits and 

 has a round pit at its base. 



The remains of spines are of rather small size, and are strongly stri- 

 ate and weakly serrate. The pectoral had the hinge arrangement of 

 Aminrus and Bhineasies. 



The single series of long conic teeth in the dentary bone is a i^eculiar 

 feature, shared by few if auy recent genera. 



Phareodon acutus, Leidy. 



Eepresented by numerous remains. The teeth as preserved are black, 

 witii white, translucent, slightly incurved apices. The dentary bones are 

 deep, incurved, and with an erect elevated point at the symphysis ; their 

 outer surface is rugose, with deep longitudinal grooves and pits of irreg- 

 ular sizes. 



Measurements. 



Depth dentary at symphysis , 009 



Depth dentary at fourteenth tooth 015 



Length of eighth tooth 005(5 



Diameter of right tooth at base 0015 



Diameter of a caudal vertebra 0085 



Length of a caudal vertebra 0055 



Six teeth in 0100 



From Upper Green Eiver. 



