170 ' COUES, 



set of the common long extensor of the digits arrested at the base of 

 the fifth metatarsal, here appears in what we hold for its true character. 

 It has the same disposition and relations in some marsupials. We 

 consider it the antitype of the extensor ossis metacarpi pollicis. At 

 first sight, especially in view of its running to the extremity of the 

 little toe, one might think it rather referable, if to any of the thumb 

 muscles, to one or both of the extensoi'S of the pollical internodes, 

 when these ax'e present, as in man. But these last appear to be de- 

 cidedly dismemberments of a common deep extensor set, of which 

 the special extensor indicis is another; and these are already amply 

 accounted for by the extensor brevis digitorum pedis. 



Flexor digitorum longus (Jibularis). — There is no tibial flexor of the 

 toes ; the fibular flexor gives off part of the large tendons that go to 

 terminal phalanges, the others being supplied by a muscle of the sole, 

 that occupies the situation of the human "flexor accessorius." The 

 flexor is a very large muscle that arises fleshy from the outer aspect 

 of the shaft of the fibula, its upper half, and thence up along the back 

 surface of the ridge that runs up the crest; and from the outer corner 

 of the crest itself; it is partially contained betwixt the gastrocnemius 

 externus and the peroneus longus. At the lower third of the leg, it 

 develops a stout tendon that runs some way upon its outer surface, 

 giving a dense glistening aponeurotic investment. The tendon passes 

 behind the middle of the heel, in a deep groove alongside the cal- 

 caneum, where it becomes flattened, and soon splits into only three 

 tendons. Two of these, that appear to be the most direct continua- 

 tions of the original tendon, run to the ungual phalanges of the first 

 and second toes ; the third divaricates more, and passes between the 

 two heads of the flexor brevis minimi digiti to its insertion into the 

 base of the ungual phalanx of the little toe. Thus the 3d and 4th toes 

 are so far unsupplied with large tendons, from this muscle. 



Flexor suhlimis (brevis) digitorum pedis. — We should judge from its 

 appearance in the specimen that it might be larger, and even supply 

 more digits, than we found to be the case in this instance. It forms 

 a short, flat, fleshy belly, lying upon, and arising wholly from, the flat- 

 tened tendon of the foregoing, with no osseous origin. It divides 

 below into two tendons only, that are lost in the digital sheaths of the 

 2d and 3d toes near their bases. 



This appears to be the antitype of the muscle of the same name 

 in the hand. The muscle has a similar disposition, and arises in 

 the same way from the tendon of the main flexor, in the opossum, 

 although in this animal it is carried half way up the leg. 



Thus far, we have seen no tendon going to the 4th digit. This is 

 supplied by a little muscle of the sole that lies in the position of 

 flexor accessorius of anthropotomy, though decidedly not to be mor- 

 phologically identified therewith. We hold it on the contrary to be 



