ANATOMY OF VERTEBRATES. 



from the first to the fifth, and in length from the second to the 

 fifth. In the Land tortoises, the fifth toe is reduced to a metatarsal 

 rudiment : the others are short and thick, fig. 

 118, each with two phalanges, the second sup- 

 porting a claw, and adapted, like those of the fore 

 foot, for burrowing. The two extremes of modi- 

 fication of the hind foot in the chelonian series 

 are presented by the Turtle and Tortoise : the 

 great comparative weight and bulk of the body 

 to be supported on dry land involve a form of 

 limb and foot resembling that in the Elephant ; 

 whence the largest kind of Land-tortoise has been 

 termed ' Testudo elepliantopus.^ 



The general homology of the pelvic bones of 

 the Crocodile has been jDreviously discussed, 

 pp. 67-69, and illustrated, figs. 55, 56, 57. The 

 serial homology of the two hffimapoph3'sial elements derives satis- 

 factory elucidation from their crocodilian condition. Of those of the 

 scapular arch, called clavicle' and 'coracoid,' in the vertebrates pos- 

 sessing both, the anterior very rarely enters into the formation of the 

 joint for the appendage ; whilst the posterior invariably does so. 



119 



Bones of lea: -iiitl 

 lout, Tcsiiulo 



Left pclTic bouca Cr.....JJ^. 



In the fcetal mammal, before the coalescence of the stunted cora- 

 coid, this relation may be seen. So in the Crocodile, the posterior 

 hffimapophysis, fig. 119, 63, combines with the ilium, 62, to the 

 exclusion of the pubis, 64, in the formation of the acetabulum, 

 repeating the articular characters of the coracoid ; whilst the 

 more slender pubis placed anterior to the joint, and abutting by its 

 mesial end against the abdominal sternum, figs. 5, 6, lo, repeats 



