281 



HOLUCEPHALI. 

 LEPTOMYLUS, Cope. 



Proceedings of tbo Boston Society of Natural History, 1B69, i>. 'M'l. 



Three species of this genus arc known (o the writer, wliicli may 1)0 

 distinguished as follows: 

 I. Mandible without apical dentinal cylinder: 



Large, massive, and not compressed L. datsus. 



11. A terminal or apical cylinder: 



Outer margin much elevated; inner much depressed; large.. L. forfcx 



Outer margin less elevated ; the inner equally so ; smaller. . . L. cookii. 



Leptomylus densus. Cope. 



Proceedings of the Boston Society of Natural History, 1869, p. 313. 



Greensand of New Jersey, No. 5 ; Birmingham, Judson Gaskill. 



Lbptomylus forfex, Cope, sp. nov. 



This chimseroid is represented by two mandibles from distant localities, 

 and probably by a maxillary bone. The form of these elements is highly 

 characteristic. The mandible is much elevated; but the elevation is confined 

 to the outer side, which rises as a lamina, causing the masticating face to be 

 nearly vertical for much of its length ; but a short extent is level to the apex. 

 There is a slight marginal swelling where the anterior outer dentinal area 

 should be, and an abrupt rise in the margin to the position occupied in 

 Lchyodus by the posterior outer area. The inner border of the masticating 

 surface is parallel to the inferior border of the jaw, except where the two 

 converge to the apex; here the entire face included between them is occupied 

 by the large syinphyseal facet. The inner dentinal area is represented by a 

 narrow acuminate patch on the inner angle of the masticatory face, ojiposite 

 the tuberosity which represents the anterior outer. The apical aTea is very 

 narrow, and extends for some distance along tlie. exterior angle ot the 

 superior face. 



Mcilsilitiiuiits. 



M. 



Lenj^th of a fragment .' •>. 1.5|j 



Lengtli to tbo posterior outer tuberosity ^- '^*^' 



Depth bebind ^■'^'^~ 



Deptli at tbe anterior outer tuberosity 0. Ooa 



Dii>tli of tbo inner face behind 0. O.U 



Lin^th of the innor dentinal area 0.014 



Width at tbo inner angle (behind) 0. 02.> 



Width near tbe 8ni)eriiir border n. 01.> 



3(j u 



