471 



6. 31. obturator extemus, . . a, 1*42 oz. 



„ . . . . b, 



)t . . . . c, 



This muscle has a common tendon with obturator 



. . 0-941 

 . . 0-66J 



0-80 oz. 



7. M. Obturator interims, . . a, 0-34 oz. 



etgemelli, b, . . 0-271 n .o q n7 



The origin of these muscles is shown in Tig. 26 (o. i. and g.), 

 where it will be observed that the origin of the gemelli occupies a larger 

 surface of the ischium than is usual in other animals. 



8. M. quadratus femoris, . . a, 1-47 oz. 



;; : : I : : m ■ ■ °' 91oz - 



This is one of the most remarkable muscles found in the Kangaroos, 

 and is intended to assist in the support of the animal when resting in 

 its usual attitude, on the tail and hind legs. It takes its origin from 

 the large triangular surface of the ischium, Fig. 25 (q.f.), and, thence 

 converging in a pyramidal mass to a point, is inserted into a special tro- 



Fig. 25. 



chanter or tubercle, developed for its reception in the middle of the 

 posterior surface of the femur. Fully two-thirds of this pyramidal mass 

 are composed of tendinous fibres, the remaining third being muscular, so 

 that the whole may be regarded as an elastic tendon. When the animal 

 sits upon its tail and legs in the manner above described, it places its 

 feet so far forward, and its tail so far back, that a mechanical observer 

 is at once struck by the apparent want of strength of the arch on which 

 the weight of the body is supported, and is disposed to come to the con- 

 clusion that the act of sitting on its tail must be a fatiguing one to the 

 Kangaroo. Observation of their habits, however, abundantly proves the 

 contrary, and shows that the animal prefers this attitude to any other. 



