1866.J ON THE ANATOMY OF THE CRESTED AGOUTI. 405 



The extensor primi internodii pollicis is also absent in the Hare 

 and Rabbit ; but the extensor secundi internodii, Prof. Huxley* says, 

 is, together with the extensor indicis, represented by one muscle. 

 However this may be, in the Hare an extraordinarily small muscle 

 arises from the ulna, and it sends an extremely delicate tendon to 

 the second phalanx of the pollex ; on one side it also sends a very 

 delicate slip to the index. 



The extensor minimi digiti comes from the external condyle and 

 the upper half of the outer border of the ulna ; its strong tendon 

 divides into two, these going respectively to the fourth and fifth 

 digits (figs. 2 & 3, E. m. d.). 



It is the same in the Guinea-pig. 



According to Prof. Huxley -f this muscle in the Rabbit supplies 

 three digits, and thus in a manner forms a double set of extensors. 

 In the Rabbit dissected by ourselves there are only two tendons given 

 off from the extensor minimi digiti, which go to the fourth and fifth 

 digits, that to the fourth coming chiefly from the external condyle. 



In the Hare this muscle appears to be almost entirely double : the 

 superior belly, which goes up as high as the condyle, supplies the 

 fourth digit ; the deeper belly, which does not reach the condyle, 

 supplies the tendon of the fifth digit. The two tendons cross. 



The extensor indicis is a very small muscle, arising from the middle 

 of the ulna, interosseous membrane, and opposite part of the radius ; 

 its tendon is inserted into the proximal phalanx of the index (fig. 3, 

 E. i.). 



In the Guinea-pig it arises from the ulna, outside the extensor 

 ossis metacarpi pollicis, and is inserted into the same part as above. 



In the Hare it is absent, unless, as Professor Huxley suggests, it 

 is represented by the extensor secundi internodii pollicis. 



Muscles of the Hind Limb. 



Gluteus maximus. We found a difficulty in assigning exact limits 

 to this muscle, as what may be considered the tensor vaginae femoris 

 is for a considerable distance inseparably united with it, while poste- 

 riorly the gluteus maximus is in close relation with a portion of the 

 biceps. 



It arises by aponeurosis from the spines of the last lumbar and all 

 the sacral vertebras, and by muscular fibre from the anterior spine 

 of the ilium and from the surface of the posterior border of the glu- 

 teus medius. 



This extensive sheet is more or less divisible into two portions, 

 the anterior of which probably repi - esents the tensor vaginas femoris, 

 and it is inserted by aponeurosis immediately superficial to the outer 

 end of what we take to be the sartorius. The posterior portion is 

 inserted exclusively into the outside of the shaft of the femur, by 

 strong tendinous fibres, especially into the prominence below the 

 third trochanter J (figs. 4 & 5, T. v.f. and G. max.). 



* Hunterian Course of Lectures, College of Surgeons, 1805. 



t Lectures above cited. 



I As Meckel observes, vol. vi. p. 355. 



