T 



of the Galapagos Tortoise 



463 



(Comp 



The muscles which move the 



shoulder are of immense size ; one^ which is probably the 

 largest in the body and entirely fleshy, arises from almost 

 the whole anterior half of the under shell and is inserted 

 into the small trochanter at the head of the humerus; the 

 others take their origin principally from the lunula and 

 scapula, except a few from the upper shell and go to be 

 inserted in and about the great trochanter of the humerus. 

 The long flexor and extensor of the forearm also arise 

 from the scapula, except for one head of the last. Below 

 these the different parts of the upper extremity have their 

 flexors and extensors, pronators and supinators very much 

 like the higher classes. Of the vertebrae, besides the 

 cervical, there are eight dorsal, four sacral and twenty-one 

 caudal. The sacrum unites firmly with the pelvis, but 

 moves freely on the last dorsal vertebra, as do the ilia also 

 by a broad surface on the transrerse processes; all of these 

 articulations have a synovial membrane, as have also, those 

 of the caudal vertebrae. The symphysis pubis, as it is usu- 

 ally called, is quite broad and in this case formed about 

 equally by the ossa pubis and the ischia, the limits being 

 quite distinct as the three coxal bones are not united by 

 ossification ; anteriorly it is flat and pointed, posteriorly 

 broad and thick ; from the anterior edge of the pubes a 

 very prominent spine arises, two and a half inches long, 

 about as large as the middle finger and directed outwards 

 to receive a muscle arising from the under shell. Obtu- 



% 



an 



circular. The femur is seven and three fourths inches 

 long and altogether considerably smaller than the hume- 

 rus ; has a single trochanter at upper extremity of mode- 

 rate size, the lower having a convex oblong form. Tibia 

 and fibula five and a fourth inches long. There are seven 



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