3i6 THE HIND FOOT OR PES. [chap. 



terminal ones) have epiphyses at both ends of the shaft 

 (see Fig. ii6, p. 315). 



In the OtariidcE, or Eared Seals, and the Walrus, which 

 use the hind feet in walking, these modifications from the 

 ordinary type are not so marked, the calcaneum having a 

 greater backward projection, and all the digits being of 

 nearly equal length. In both there is a large sesamoid on 

 the tibial side of the tarsus. 



In the greater number of the animals of the order In- 

 SECTivoRA the tarsus is quite normal, and there are five 

 digits, all with curved, pointed, moderately developed 

 ungual phalanges, the hallux being the shortest. In the 

 Mole, the pes is narrow, having none of the modifications 

 of structure observed in the manus, except that there is 

 an unusually large slender sesamoid on the tibial side of 

 the tarsus, corresponding to the falciform bone of the fore 

 limb. In the Water Moles {Myogak), the pes is remark- 

 ably large and almost fin-like. 



In the African genera Fetrodromus and Rhyuchocyon^ the 

 hallux is only represented by a rudimentary metatarsal. 

 The last-named animal has a remarkably elongated pes, 

 produced partly by the length of the metatarsals, and partly 

 by a peculiar elongation of all the bones of the distal row 

 of the tarsus, the cuboid, and three cuneiform bones. Con- 

 trary to what occurs in the Galagos, the navicular and cal- 

 caneum are of normal proportions. 



Order Chiroptera. — The tarsus is very short ; the tuber 

 calcanei a slender curved process ; the metatarsals are 

 equal and rather short ; the phalanges elongated and sub- 

 equal in length, the hallux being rather the shortest ; the un- 

 gual phalanges are long, curved, compressed, and pointed. 



Order Rodentia. — The structure of the pes varies much in 

 different members of this order. In the Beaver, as in most 



