PLIOCENE HAKES FROM IDAHO — GAZIN" 



113 



Comparison between the Hagerman specimens and topotype ma- 

 terial of n. vet'us in the collections of the California Institute of 

 Technology shows the Idaho form to be very nearly the same size as 

 H. vetus, comparable in this respect with specimens of Lepus town- 

 sendii. Two of the 



jaw portions appear 

 to be somewhat more 

 robust than in H. 

 vetus and in U.S.N.M. 

 no. 12G20 (fig. 1«); 

 the lower tooth row 

 is slightly longer and 

 the individual teeth 

 relatively a little 

 wider. Moreover, 

 several of the third 

 lower premolars, 

 though similar in pat- 

 tern to those of H. 

 vetus, are a little 

 larger and somewhat 

 more rounded antero- 

 internally, giving the 

 anterior portion o f 

 the tooth a relatively 

 greater width. Two 

 isolated P^ from near 

 Hagerman show a 

 deep anterior re- 

 entrant enamel fold 

 directed postero-exter- 

 n a 1 1 y and a much 

 shallower groove ex- 

 ternal to this, much 

 as in n. vetus. The 

 upper molarif orm 

 teeth are similar to 

 those in the Nevada 

 specimens. 



The Hagerman form appears somewhat more advanced than the 

 Thousand Creek Eypolagus vetus, as suggested by the slightly 

 greater relative width of the lower teeth in one of the jaws and per- 

 haps by the greater average robustness of the jaws of the Idaho form. 

 In all probability a single line of descent is represented, the Middle 

 Pliocene form in Nevada giving rise to the larger of the late Plio- 



FiGunB 2. — Hypolagus limnetus, new species : SkuH 

 and mandible, type specimen (U.S.N.M. no. 12619) ; 

 dorsal, v€utral, and lateral views of skull and 

 lateral view of right ramus (reversed) of mandi- 

 ble ; X 1. Hagerman lake beds, Upper Pliocene, 

 Idaho. 



