3^0 SMITHSONIAN MISCELLANEOUS COLLECTIONS [vOL. 45 



METACARPUS 



There are few points of interest about the metacarpus of either 

 the Leporidse or the Ochotonidse ; both have metacarpi of a general- 

 ized mammahan type. The first metacarpal is very short in both 

 families. The fifth metacarpal is about twice or about two and a 

 half times the length of the first. The middle metacarpal is the 

 longest, but not much longer than the two subequal adjacent ones. 

 The middle metacarpal is relatively longer in the Leporidse than in 

 the Ochotonidje, with respect to the two metacarpals on either side 

 of it. 



The metacarpus, as a whole, is longer in the Leporidse than it is 

 in the Ochotonidse. The width of the three middle metacarpals at 

 their bases is contained about two and one-half times the length of 

 the middle metacarpal in all the genera except Pcntalagiis. In the 

 Ochotonidse, however, and in Pcntalagus of the Leporidse the basal 

 width of the three middle metacarpals taken together is contained 

 only about one and one-half times in the length of the middle meta- 

 carpal. 



PHALANGES 



The phalanges are relatively longer in the Leporidse than in the 

 Ochotonidse. In both families the length of the three phalanges of 

 the middle digit about equals the length of the middle metacarpal, 

 which bone, as noted above, is relatively longer in the hares and 

 rabbits than in the pikas. 



OS INNOMINATUM 

 Leporid.^i 



The OS innominatum in all the genera of the Leporidse is generally 

 uniform in shape, differences being slight and apparently of not much 

 importance, yet they are fairly constant for some genera or groups 

 of genera. 



In the genus Lcpus, the ilium is broad and shovel-like ; the antero- 

 superior angle of the crest is rounded off, but not obliquely so as in 

 the case of the other genera. The distance from the anterior edge 

 of the acetabulum to the most anterior point of the ilium, is less 

 than the distance from the same point to the most distant part of the 

 ischium, while in all the other genera the distance from the anterior 

 edge of the acetabulum to the most distant point of the ilium is equal 

 to or a little greater than the distance measured from the same point 

 to the most distant part of the ischium. 



