VII.] 



INSECTIVORA. 



77 



gives off a pair of wing-like processes, behind which the first 

 pair of ribs are attached. It is distinctly separated from the 

 mesosternum, which consists of five segments of nearly equal 

 width. The xiphisternum has a broad oval cartilaginous ex- 

 pansion posteriorly, not shown in the figure, 

 which is taken from a dried specimen. 



As the clavicle is supported at the 

 anterior extremity of the elongated pre- 

 sternum, it is widely separated from the 

 first rib, and the anterior extremities are 

 brought into such close juxtaposition with 

 the head, that the animal appears to have 

 no neck. 



In the Chiroptera, the sternum pre- 

 sents a considerable general resemblance 

 to that of Man. The presternum is large, 

 trilobate in front, and strongly keeled. 

 In many of the Insectivorous Bats the seg- 

 ments of the mesosternum are (at least in 

 adults) firmly ankylosed together, but in the frugivorous 

 Bats {Pteropus^ &c.) they continue separated. 



In the RoDENTiA, the sternum is long and narrow, consist- 

 ing of a presternum (which is generally broad in the forms 

 which have the clavicle well developed, as the Rats, Beavers, 

 &c.), a mesosternum of three, or more usually four, seg- 

 ments, and a long xiphisternum, with a broad cartilaginous 

 terminal expansion. The segments of the mesosternum 

 often have epiphyses at each end. 



The presternum is compressed and produced forwards in 

 those species in which the clavicle is absent or rudimentary, 

 as the Aguti, the Hares, and the Capybara. In the latter 

 it much resembles that of the Horse or Tapir. 



Order Ungulata. — In the Rumiiiantia there are usually 



Fig. 34. — Sternum of 

 Common Mole ( Tnl- 

 pa europcea). ps p'e- 

 sternum ; ms meso- 

 sternum ; xs xiphi- 

 sternum ; c point of 

 attachment of cla- 

 vicle. 



