86 
CHIMiEROIDEI. 
The right vomerine tooth of a large species of Edaphodon , from 
the Cretaceous of Columbus, Mississippi, now in the Museum of the 
Academy of Natural Sciences, Philadelphia, is described as the 
mandibular tooth of a distinct genus and species, Eumylodus 
laquecttus , J. Leidy, Ext. Vert. Eauna W. Territ. (Pep. U.S. Geol. 
Surv. Territ. vol. i. 1873), p. 309, pi. xix. figs. 21, 22, pi. xxxvii. 
figs. 13, 14. 
The genus Diphrissa , E. D. Cope (Yert. Cret. Form. West, 1875, 
p. 283), is founded upon a mandibular tooth differing only from that 
of the typical Edapliodon in the presence of a single outer tritor—a 
feature noted above in Edaphodon reedi. Two species are recognized 
from the Cretaceous Greensand of New Jersey, the type being 
D. solidula, previously named Ischyodus solidulus (E. D. Cope, Proc. 
Amer. Phil. Soc. vol. xi. 1869, p. 244). The description of the 
second species, D. Jatidens, Cope, accompanies the generic diagnosis ; 
and both of the type specimens are in the Cope Collection, Phila¬ 
delphia. 
The following genera and species appear to the present writer to 
be probably founded upon indeterminable fragments of the teeth of 
Edaphodon. They were obtained from the Cretaceous Greensand 
of New Jersey, and are preserved in the Cope Collection :— 
Bryactinus amorphus , E. D. Cope, Yert. Cret. Form. West (1875), 
p. 282. 
Isotcenia neoccesariensis, E. D. Cope, ibid. p. 293. 
The following genus and species is founded upon a palatine and 
vomerine tooth, of which the former appears to be a broken Edapho- 
dont tooth:— 
Mylognathus prisons, J. Leidy, Proc. Acad. Nat. Sci. Philad. 
1856, p. 312, and Trans. Amer. Phil. Soc. [2] vol. xi. 
(1859), p. 153, pi. xi. figs. 24-30.—Tertiary Lignite ; 
Nebraska. 
The following genus, with three species, is founded upon an 
imperfect mandibular tooth showing onlj- an inner tritor. A palatine 
tooth having long, narrow, outer and inner tritors, is doubtfully 
associated with this :— 
Leptomylus densus , E. D. Cope, Proc. Boston Soc. Nat. Hist, 
vol. xii. (1869), p. 313.—Greensand ; New Jersey. [The 
type species ; E. D. Cope Collection, Philadelphia.] 
