237 



Measurements. 



M. 



LiMi^lli nllli,. Inst iii:ixill:ir.v tiidlli (1.003 



Loiif? (li:iim^t<'r of the Imsis (if tlic' last maxillary tooth 0. GUI 



Deiith of the maxillary bone at the basis of the last maxillary tooth 0.01'J 



TETHEODUS, Cope. 



Prcmaxillary hone a petrous mass, without teeth; the maxillary with 

 teeth in a single row, the anterior much enlarged; dentary with a single 

 series, one anterior tooth much enlarged. Apices of teeth with trenchant 

 edges. 



A genus chietly dilFering from Eiichodus in the absence of th(! large tooth 

 at the extremity of the prcmaxillary bone. 



Tetueodus pepiiredo, Cope. 



r>oth prcmaxillary and portions of the maxillary and dentary bones of one 

 specimen represent tliis species. They show it to have been a powerful fish, 

 of the size of the Encliodus petrosus below mentioned. The premaxillaries arc 

 excavated by the usual three oblique fossae above on the inner side. The alve- 

 olar face is a ridge extending oblirpiely across from a tuberosity on the inner 

 side, behind the apical tuberosity. There is no surface for the attachment 

 of a tooth, and no scar or other trace of the former existence of one. The 

 maxillary underlaps it by an oblifjue suture, and supports a large tooth simi- 

 lar to that at the end of the prcmaxillary in Enchodus, behind which are seen 

 the crescentic scars of the previously shed teeth. The outer lace of the basal 

 cementum of this tooth is perfectly smooth. The distal portion of the dentary 

 hone is toothless ; its anterior tooth is a fang, with the base excavated in front ; 

 and an angle rising from the external side of it becomes a latcro-exterior 

 cutting-edge of the crown to the ape.x. The inner posterior, or more convex, 

 face of the tooth is regularly and closely striate-grooved. On one dentary, 

 there are three or four small denticles in front of it on the outer side. The 

 smaller teeth have twtj cutting-edges, and tin; posterior liice at (he Ijase is 

 grooved striate. This regular grooving, as well as the large size of the lirst 

 maxillary, distinguishes this fish from the I'/iasganodus anceps. 



t 



^ 



o 



Measiirements. 



ir. 



Leugth of the preiiiaxillary bono above 0. 0*5 



Depth of till! preiiiaxillary bone above (1. 0;W 



Width of the basis at tlie lirst maxillary tooth 0.010 



