CHIROPTEKA. 321 



Rhinohptuda alone do these bones form a symphysis 

 (Dobson). There is usually a strongly developed " pectineal " 

 process, near the acetabular end of the anterior border 

 of the pubis, and which in some genera (e.g. Phyllorhina, 

 triienops), is prolonged so far as to unite with a process from 

 the superior extremity of the ilium, forming a pre-acetabular 

 foramen, as large as, or larger than, the thyroid foramen, an 

 arrangement unique among Mammals. 



In many of the RODENTIA, as the Beaver, the ilia are 

 markedly trihedral, with sides of nearly equal extent; but 

 in the Hares the outer (acetabular) border is almost obso- 

 lete, the gluteal and iliac surfaces are confluent, and both 

 face outwards, and the internal surface is largely deve- 

 loped above the sacral attachment. 



The pubes and ischia are always largely developed, flat, 

 and diverging posteriorly, the obturator foramen is of con- 

 siderable si/e, and the symphysis is long, and usually 

 becomcs osseous ; in the Guinea Pig (Cavia), however, it 

 remains ligamentous, and the bones are widely separated 

 during parturition. 



Order UNGUI.ATA. In the Pecora the pelvis generally is 

 elongated. The ilium is expanded and everted at the 

 upper extremity ; but between the sacral attachment and the 

 acctabulum it is much contracted, and its borders rounded, 

 so that the divisions of its surfaces are no longer distinct. 

 There is usually a deep oval depression above the ace- 

 tabulum, just within the attachment of the rectus femoris 

 muscle. The anterior outlet forms a regular oval with the 

 long diameter between the sacrum and symphysis. The 

 latter is very long, including a considerable portion of the 

 ischia. The margins of the bones are completed by large 

 epiphyses in this region, but ultimately coalesce across 

 the middle line. The ischia are much developed ; the 



