1882.] ANATOMY OF ERETHIZON DORSATUS. 283 



The extensor carpi radialis brevior is a larger muscle, and has a 

 stronger tendon, than that last noticed, which overlaps it at its 

 origin. It goes to the third metacarpal. 



The extensor communis cHgitorum goes as usual from the external 

 condyle to the four outer digits. 



The extensor carpi ulnaris takes origin from the external condyle 

 and adjacent parts of the ulna, and goes to the base of the fifth 

 metacarpal. 



The extensor ossis metacarpi polUcis is large and strong ; it takes 

 origin from the adjacent sides of the radius and ulna, but mainly 

 from the ulna and the strong interosseous ligament. Its insertion is 

 as usual. 



The extensor minimi digiti, arising from the external condyle, 

 sends tendons to the fourth and fifth digits. 



The extensor indicis is very delicate ; it takes origin from the 

 middle of the exterior surface of the ulna, and sends its tendon to 

 the index. 



Muscles of the Hind Limb. 



The gluteus maximus and gluteus minimus I found to be quite 

 similar to those of the Agouti '. 



The gluteus medius is also as in the Agouti, save that the part of 

 it which is inserted into the hinder side of the great trochanter is 

 more distinct. I did not observe any distinct scansorius. 



The biceps consists of two parts, which are very similar to those 

 of the Agouti : the first part arises from the sides of the first four 

 caudal vertebrae, and is inserted by a strong tendon into the outer 

 side of the patella ; the second part arises (being mainly tendinous 

 at its origin) from the tuberosity of the ischium, external and 

 superficial to the origin of the semimembranosus. It is inserted 

 by fascia into the patella, the tuberosity of the ischium, the head of 

 the fibula, and the external malleolus, and into the fascia which 

 invests the outside of the leg. 



The most slender accessory muscle of the biceps, or tenuissimus, 

 takes origin from the strong fascia which binds down the dorsal 

 caudal muscles at the root of the tail, on a line with the great 

 trochanter, and at the anterior end of, and covered in by, the origin 

 of the first part of the biceps. It is inserted into the heel and inner 

 side of the sole of the foot ; in its course it lies close to the hinder 

 border of the second part of the biceps ; at its insertion it unites 

 with the plantar fascia, having a certain adhesion to the inner side 

 of the tuberosity of the os calcis, and more to the plantar surface of 

 the extra tarsal ossicle. 



The semimembranosus also consists of two parts : one part, thick 

 and fleshy, arises from the tuberosity of the ischium and the ramus 

 below it. It goes to the upper half of the tibia (covered in by the 



^ See P. Z. S. 1866, p. 405. What, was therein taken to be the tensor vaginm 

 femoris I now beheve to be the sartor ius. 



