232 BULLETIN NO. VII. 



only after birth. An os centrale is found in the carpus. The 

 outer or acetabular border of the ilium is almost obsolete, and 

 the gluteal and iliac surfaces are confluent. 



The tibia is very long. There is a third trochanter below 

 the trochanter major of the femur. The fibula is slender and 

 distally united with the tibia, while above, it is united by an 

 interosseus cartilage. The hallux or inner toe is wanting, and 

 the metatarsals are elongated. 



COMPARISON OF CRANIA OF AMERICAN HARES. 



The skulls of Lepus callotis and of L. californicus are very 

 similar. L. californicus appears to have the mandible more 

 slender, with the margin between angle and condyle more 

 deeply excavated, otherwise the two species agree quite fully 

 and differ from L. timidus var. arcticus and L. campestris in 

 the very long and slender nasals, the less strong curvature of 

 the crani-facial axis and some other differences. 



The skulls of L. aquaticus and L. palustris carry out the 

 peculiarities of the L. sylvaticus group to an extreme. The 

 lower jaw becomes solid and broad. The supraorbital frontal 

 processes are fused completely with the skull. The hamular 

 process of the zygomas are enlarged, thus giving greater 

 security to the glenoid fossa. In both, the maxillary part of 

 the inter- alveolary bridge is enlarged rather than the palatal 

 portion. The constriction of the nasals just prior to the end 

 is also noticeable. 



The differences between the skulls of Lepus sylvaticus and L. 

 auduboni are not of a very tangible character, if we may judge 

 from Prof. Baird's figures. The comparison is not facilitated 

 by the fact that the skull of the latter figured was evidently 

 that of a young animal while that of L. sylvaticus is an old one 

 with sutures closing and frontal processes united with the 

 skull. (See Baird's Mammals, PL Iviii.) The interparietal of 

 the latter is either ignored or has anchylosed with the neigh- 

 boring parts. But we know that usually at least this anchy- 

 losis does not take place even in old L. sylvaticus. Other 

 apparent differences may, probably, be eliminated in like man - 

 ner. Baird's figure of the basis cranii in the one case is in- 

 complete but shows the absence of two teeth present in the L 

 sylvaticus. 



