948 MONOGRAPHS OF NORTH AMI KICAN RODENTIA. 



Genus COLOTAXIS Cope. 



I ,11. Pal. Bull. ii". 15, 1-73, 1. 



"Inferior molars 3; crown plicate, with two connected cusps with crescentic sec- 

 lion, 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 CKISTATUS Cope. 



Colotaxis cristatus Cope, Pall. Bull. no. 15, 1873, 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". 



HYSTEICOMORPHA. 



HYSTRICIDiE. 



11 VSTR1X VENUSTUS Leidy. See anted, p. 31)7. 

 ERETHIZON CLOACINUM Cope. See anted, p. 39*. 



CASTOROIDID^E. 



CASTOEOIDES OHIENSIS Foster. See anted, p. 42-1. 



Incertce sedis. 

 Genus AMBLYEHIZA Cope. 



Amblyrhiza Cope, Proc. Acad. Nat. Sci. Phila. 1868, 313. See also anted, p. 421. 



AMBLYUHIZA INUNDATA Cope. 



Amblyrhiza iiiundata Cope, Proc. Acad. Nat. Sci. Phila. 18G8, 313; Proc. Amer. Phil. Soc. Phila. 1869, 183, 

 pl. iv, pi. v, fig. 1. 



Genus LOXOMYLTJS Cope. 



Loxomylua Cope, Proc. Auaer. Phil. Soc. Phila. 1869, 186. (See also anted, p. 421.) 



LOXOMYEUS LONGIDENS Cope. 



Loiomylus longidens Cope, Proc. Araer. Phil. Soc. Phila. 1869, 187, pl. v, figs. 2, 3. 



LOXOMYLUS LATIDENS Cope. 



LozomtjUi* latidens Coin:, Proc. Amer. Phil. Soc. Phila. 1870, 608. 



As already noted on a previous page of this work (p. 421), the genera Amblyrhiza and 

 Loxomi/liis, together with the species referred to them, were based by Professor Cope 

 (/. c.) 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 Chinchillidce, and also to Castoroidi- 

 dw, nearly equalling the latter in size, to which group they may prove to be referable. 



