1902.] Alattheiv, A Horned Rodent from Colorado Miocene. 3*^5 



more hypsodont than in the American Steneofibers; the 

 molars have but one internal and one external enamel inflec- 

 tion (fossettes in the type 

 specimen). The upper pre- 

 molar has three external and 

 the lower premolar three in- 

 ternal inflections, as in Steneo- 

 I'fZtI f^^^'^ ^^^ Castor. The position 

 of Eucastor is very doubtful ; 

 if, indeed, it is a true Castorid at all, it cannot be very nearly 

 allied to either Castor, or Steneofiber. To this genus and 

 species probably belong, besides the type, parts of two lower 

 jaws in the Cope Collection. 



Fig. II. Eucastor tortus Leidy. 

 molars x \. No. 8332 (Cope Coll.) Loup Fork 

 (Republican River Beds), Nebraska. 



OTHER CASTORID^ FROM THE LOUP FORK. 



The two isolated teeth which form the type of Leidy's 

 Hystrix vennstiis, if they are really from the Loup Fork, are 

 much more likely to be Castorid than Hy- 

 stricid, the latter not being likely to occur 

 as far down in the Tertiary of the Western 

 States as the Miocene. Possibly with these 

 species should be associ- 

 ated a broken tooth from 

 inf:f.^Uppir'p/e'';^ora';x|: the Colorado Loup Fork, 



No. 0^64. Loup Fork r j_i • j 



(Pawnee Creek Beds), Col- of thC SamC SlZC and gen- 



°"'^°' eral proportions and pat- 



tern as H. venustus. Another isolated tooth 



r , 1 1 1 TVT z- I ^ig- '3- ? Castorid, indet. 



from the same beds, J\o. 9304, represents ax?. Loup Fork (Pawnee 



,,, 1 .. 1 i-,,ii Creek Beds), Colorado. 



species probably undescribed, a little larger 



than 5. montanus, more hypsodont and of more complicated 



pattern. A third specimen is part of a lower 



(€^V^{^/h(^ j^^ with mg-g, the latter just emerging. 



'^ jj.,u> \0)l(/J[\l(^ This is much more brachydont than Steneo- 



... , fiber, although of somewhat the same gen- 



Fig. 14. ? Castorid, indet. ' ' ° ° 



Last two lower molars X ?. ej-al pattcm, and somcwhat smaller than 



Loup rork (rawnee Creek -"^ 



Beds), Colorado. -(^j^g dcscribcd species. The style of the 



teeth suggests Spalax rather than any other genus of Rodentia 

 with which I am acquainted. 

 [August, igo2.] 20 



