283 



columns issue on the ifiiiuliiig-face along the oiit<!r bonier, and arc not parallel 

 in their courses, l)ut divergent from nearer origins. The inner lace behind 

 the posterior exit of the apical column is excavated as if tor the application 

 of another bone ; hence, I have suspected tliat the piece described might be 

 premaxillary. The grinding-face is convex at the middle, but divided into 

 two ))lanes posteriorly: the outer narrow and elevated; the inner oblicjue, 

 and separated In' an obtuse angle from the excavation of the inner side. 



Measurements. 



a. 



Li-i)t!lli of tlio fiasmiiit 0.042 



Lciigdi of t lie fi:ij;uieiit to the posterior cxposim^ of the apical [:oluiiiM 0. OiO 



Deptli at till- eiul of the apical angular riilge (l. OIH 



Width opposite the eud of the apical angular ridge (I. OKi 



Width of the fragment I)ebind 0. 00t» 



This species is associated in my collection with specimens of Isc/ii/odus 



smochii, \n\\ cannot be the premaxillary of that species, since that element 



occurs in the same series, and is similar to that observed in other species 



of the genus. 



DIPHRISSA, Cope, genus novum. 



Established on peculiarities exhibited l)y the mandibular dentition 

 There is a large inner area of dentinal tubules, and a terminal one issuing 

 near the apex. There is but a single small external area In Ischyodus, 

 there are two such areas; but, in other respects, the mandibles of the two 

 genera are similar. 



DlPHRISSA SOLIDULA. 



Ischyodus solidtilus, Cope, Proceedings of the Anicricau Philosophical Society, 1869, p. 244. 



Greensand of New Jersey, No. 5, at Hornerstown ; from John G. 

 Miers. 



DiPURISSA LATIDENS, Cope. 



Indicated by a mandibular ramus, derived from the same locality and 

 donor as the last species. Anterior portion or beak narrowed; the apical 

 area tlaf, or crescent-like. Inner area very wide, leaving but a narrow border 

 on ilie outer side of it. This band is but little ()l)li(pie, the edge I)eiug 

 slightly elevated, and does not exhibit any dentinal tirea. The single outer 

 column issues near the border; its posterior edge in transverse line with the 

 anterior edge of the inner area, its anterior extremity extending a short dis- 

 tance l>e\()nd. The anterior liordcr of (lie inner area is liroad and ol)luse. 



