HOLOCEPHALI. 121 



rowed and truncate in front, and dentinal areas large, especially 

 posterior. Superior groove deep, and outer face extensive and 

 longitudinally ridged. 



Formation and locality. Known from eight lower jaws, some 

 with palatals, of which seven mandibulars and one palatal are in 

 the American Museum of New York. They are from the marl 

 [Hornerstown marl, K.] at Birmingham and Hornerstown. Cope 

 also had an example from Medford. I have not seen any 

 material. 



Edaphodon mirificus Leidy. 



Bdaphodon mirificus Leidy, Proc. Acad. Nat. Sci. Phila., 1856, p. 221. Bur- 

 lington Co., N. J. Cretaceous Greensand. 

 Leidy, Rep. U. S. Geol. Surv. Terr., I, 1873, pp. 306, 350, PI. 37, figs. 



6-12 (types). 

 Hussakof, Bull. Amer. Mus. N. H., XXV, 1908, p. 38, PL 2, fig. 3 (Cope's 

 material) . 

 ischyodus mirificus Cope, Rep. U. S. Geol. Surv. Terr., II, 1875, pp. 285, 291. 



(Barnesborough and Hornerstown, N. J. Greensand No. 5.) 

 Ischyodus monolophus Cope,- Proc. Boston Soc. N. H., XII, 1869, p. 314. 

 Barnesboro (Barnesborough), Gloucester Co., N. J. Greensand. 

 Cope, Rep. U. S. Geol. Surv. Terr., II, 1875, pp. 285, 289 (type, Green- 

 sand No. 5). 

 Ischyodus gaskillii Cope, 1. c, pp. 285, 290. Birmingham, Greensand of New 

 Jersey, No. 5. 



Mandibulars a little more than twice as long as deep, rami 

 converging in a curve and ending in a long, symphyseal, bird-like 

 beak. Outer surface of each mandibular concave medianly and 

 convex above and below. Outer profile concave anteriorly, then 

 sloping up convexly, and below and behind convex. Inner sym- 

 physeal edge beveled, flat and rather narrow, and below this and 

 posteriorly slightly convex with several longitudinal striae. Oral 

 surface of beak concave and posteriorly forms plane sloping in- 

 wards, this largest dental area. Anteriorly and externally an- 

 other small rounded dental area, situated on a slight convexity, 

 and followed back by a concavity at first rather spacious and then 

 narrow where it separates a third dental area. Latter situated 

 just inside external crest of mandible and about opposite middle 

 in length of largest dental area, and elongate, though same width 

 as anterior dental area about twice as long. A fourth short, nar- 



