948 MONOGRAPHS OF NORTH AMERICAN RODENTIA. 
Genus COLOTAXIS Cope. 
Colotaxis Corr, Pal. Bull. no. 15, 1873, 1. 
‘Inferior molars 3; crown plicate, with two connected cusps with crescentic sec- 
tion, on the outside, each of which gives rise to two transverse crests, which are 
unconnected. Of these crests, the anterior and posterior are marginal and less devel- 
oped than the median pair. Intervals deep, without cement.” 
COLOTAXIS CRISTATUS Cope. 
Colotaxis cristatus Core, Pall. Bull. no. 15, 1878, 1. 
«“ Anterior molar narrower than the others, the cusps partly alternating, the con- 
necting crests of the exterior wall internally placed, the transverse crest from the pos- 
terior forming a V. Anterior cusps well separated. Enamel of all the molars smooth.” 
Anterior face of incisors regularly convex. From the “ Tertiaries of the Plains”. 
HYSTRICOMORPHA. 
HYSTRICIDA. 
HYSTRIX VENUSTUS Leidy. See antea, p. 397. 
ERETHIZON CLOACINUM Cope. See anted, p. 398. 
CASTOROIDID. 
CASTOROIDES OHIENSIS Foster. See anted, p. 424. 
Incerte sedis. 
GrENus AMBLYRHIZA Cope. 
Amblyrhiza Corer, Proc. Acad. Nat. Sci. Phila. 1868, 313. See also anted, p. 421. 
AMBLYRHIZA INUNDATA Cope. 
Amblyrhiza inundata Cops, Proc. Acad. Nat. Sci. Phila. 1868, 313; Proc. Amer. Phil. Soc. Phila. 1869, 183, 
pl. iv, pl. v, fig. 1. 
GENus LOXOMYLUS Cope. 
Loxomylus Core, Proc. Amer. Phil. Soc. Phila. 1869, 186. (See also anted, p. 421.) 
LOXOMYLUS LONGIDENS Cope. 
Loxomylus longidens Core, Proc. Amer. Phil. Soc. Phila. 1869, 187, pl. v, figs. 2, 3. 
LOXOMYLUS LATIDENS Cope. 
Loxomylus latidens Corr, Proc. Amer. Phil. Soc. Phila. 1870, 608. 
As already noted on a previous page of this work (p. 421), the genera Amblyrhiza and 
Loxomylus, together with the species referred to them, were based by Professor Cope 
(1. ec.) on detached teeth from the bone breccia of caves, from Anguilla Island, West _ 
Indies, and are as yet too imperfectly known to render their affinities fully apparent. 
In the structure of the teeth, they are allied to the Chinchillida, and also to Castoroidi- 
de, nearly equalling the latter in size, to which group they may prove to be referable, 
