PLIOCENE HARES FROM IDAHO GAZIN 115 



tinctly shorter dorsoventrally. The tympanic bulla is of consid- 

 erable size, much larger than in S. nuttalli grangeri and nearly as 

 large relatively as in B. idahoensis. The space between the bullae 

 is less than in the cottontail and the basi-occipital is about one- 

 fourth longer. The ectopterygoid fossae are about the same dis- 

 tance posterior to the cheek teeth as in S. nuttalli grangeri but much 

 farther forward from the foramen magnum, apparently because of 

 the greater inflation of the bullae. The posterior nasal opening is 

 relatively deep and distinctly narrower transversely than in Sylvi- 

 lagus^ much as in Rom^rolagus. The palatines form a more distinct 

 ledge or ridge inward from the posterior molars on each side than 

 in Sylvilagus. The palatines on either side of the nasal opening 

 are nearly parallel in the fossil, whereas in Sylvilagus the widest 

 portion of the opening is to the front, converging posteriorly. The 

 bony palate between the grinding teeth is short 

 as in Sylvilagus^ the palatal processes of the .-/ -!- ^ '^'^- ^ 

 palatines being more reduced than in Rom- %£• . ^ -^ 



erolagus. Only a part of the right jugal is ^ 



preserved in the fossil, but this portion is a „ 

 little deeper than in S. nuttalli grarigeri^ and ^^^v^,,^,^ ^.^ 

 anteriorly the outward flare of the ventral sur- i 



face is less pronounced. The postorbital proc- ^,^^^^^ s.-Hypoia- 

 esses are broken away, but on both sides the gus umnetus, new 



length of the break is short, suggesting that 'P''^''= "' ^^" 



» _ ' f^*^ *^ supenor d e n t i- 



the process consisted only of a backward-pro- tion ; h, right in- 



jecting spur. ■ f*^"^'- d"^«t/;o'^; 



J fr< 1. _ ^ ^ _ type specimen 



The upper teeth in the fossil are nearly identi- (u.s.n.m. no. 



cal in size with those in Sylvilamis nuttalli qran- i26i9) ; occlusal 



if iJ J _ views, X 2. Ha- 



geri^ although the diastema between the incisors eerman lake beds, 



and cheek teeth is much shorter. The principal \^^ll ' Pliocene, 



incisors are more recurved than in the cottontail, 

 and the groove on the anterior surface is more nearly median in posi- 

 tion. The small posterior incisors show no differences other than 

 being directed backward to a greater degree. The enamel pattern of 

 P^ (fig. 3a) differs from that in the recent Idaho cottontail in having 

 only two reentrant folds on the anterior surface. Both folds are 

 relatively shallow, the more lingual fold being the deeper. In S. nut- 

 talli grangeri there are three distinct anterior folds, the middle fold 

 being deeper than the others, and in addition there is a very shallow 

 groove near the external margin. The succeeding molariform teeth 

 in the fossil resemble very closely those in the cottontail. The 

 crenulated medial lingual folds in these teeth extend almost as far 

 externally as in S. nuttaUi grangeri. 



The mandible shows about the same proportions as in Sylvi- 

 lagus nuttalli grangeri.., although the diastema between the incisor 



