294 THE PELVIC GIRDLE. [chap. 



the case may be. Hence they are usually more largely 

 developed in the male than in the female. 



In the Whalebone Whales they usually have a projecting 

 angle placed about the middle, near which, in some species, 

 a second small bone, which probably represents the femur, 

 is attached by ligament (see Fig. 112, p. 305). In a full- 

 grown male Rorqual {Balcenopiera muscuhis), sixty seven feet 

 in length, each pelvic bone was sixteen inches long. In the 

 Greenland Whale {BalcEua mysticetus^) they are rather shorter 

 and stouter. As might be expected, from the rudimentary 

 character of these bones, they vary considerably in size and 

 form in different individuals of the same species, and often 

 on the two sides of the same animal. 



In the Dolphins, they are generally smaller, and more 

 simple than in the Whalebone Whales, and usually quite 

 straight, though sometimes arched, or presenting a sigmoid 

 curve. 



Order Edentata. — In the Sloths, the pelvis is very short 

 and wide, with tolerably broad flattened ilia, and slender 

 pubes and ischia, inclosing a large oval thyroid foramen, 

 the inferior boundary of which, and the extremely narrow 

 ossified symphysis, are formed by the pubis alone. The 

 spine of the ischium is produced backwards to unite with 

 the transverse processes of some of the pseudosacral ver- 

 tebrae, inclosing a sacro-sciatic foramen. The sacro-iliac 

 articulation is commonly ankylosed. 



In all the other Edentates the pelvis is more or less elon- 

 gated, the ilia trihedral, the ischia largely developed, the 

 l)ubes slender, the symphysis exceedingly short, but usually 

 ossified, and the thyroid foramen large. In all, except Oryc- 

 teropus^ the ischia unite with the vertebral column. This 

 union is carried to its greatest extent in the Armadillos, in 

 which animals the broad transverse processes of as many as 



