REPORT ON THE MARSUFIALIA. 57 



There is no adductor of the index in the Cuscus. The fibrous raphe (fig. 5, r.) is 

 attached to the outer aspect of the base of its proximal phalanx, and the lower end of 

 this probably represents the missing muscle, which has thus been converted into fibrous 

 tissue. 



The adductor hallucis (fig. 5 p 1 ) is the most powerful of the three muscles of the 

 hallux, aud at the same time it is the most complex in its arrangement. It has a double 

 origin — (a) from the base of the metatarsal bone of the index, and from the tibial side of 

 the fibrous raphe ; (b) by a few fibres from the aponeurosis which clothes the dorsal 

 aspect of the first dorsal interosseous muscle. The fleshy fibres soon arrange themselves 

 into three slips which we may distinguish by the terms plantar, intermediate, and dorsal, 

 and by these it is inserted. The plantar slip is attached to the outer of the two sesamoid 

 bones along with the outer head of the flexor brevis hallucis. The intermediate slip ends 

 in a long delicate tendon, and is inserted by this into the fibular side of the minute 

 distal phalanx, and the dorsal portion ends in the extensor tendon. 



The adductor minimi digiti (fig. 5, p 5 ) is a fan-shaped muscle which arises by its base 

 not only from the greater extent of the fibular margin of the fibrous raphe but also from 

 the ligamentous textures at the base of the third and fourth metatarsal bones. From 

 this its fibres converge, and it is inserted into the tibial side of the base of the proximal 

 phalanx of the minimus. 



The adductor annularis (fig. 5, p 4 ) is small in comparison with the preceding muscle, 

 but it has the same triangular shape, and it is placed at right angles to the toe upon 

 which it operates. It arises from the fibular margin of the distal portion of the raphe, and 

 also from the base of the first phalanx of the index. Arching over the base of the medius, 

 it is inserted into the tibial side of the base of the proximal phalanx of the annularis. 



The line towards which these muscles adduct the toes is manifestly one drawn 

 through the index, and this, whilst it corresponds with the human foot, is an exception 

 to the general rule that abduction and adduction are effected with reference to a line 

 drawn through the medius. 



The intermediate layer (figs. 5, 6, f l to / 5 ). — There are five muscles composing this 

 layer, one to each toe, and they correspond with the same muscles in the preceding ani- 

 mals. Each muscle consists of two slips, and these are inserted one into each sesamoid 

 bone at the base of the digit with which they are associated. 



The flexor brevis hallucis (f 1 ) is one of this group, but owing to the position of the 

 hallux it is somewhat separated from its neighbours. It arises by a single tendinous 

 orioin from the under surface of the scaphoid, and dividing into two heads it is inserted 

 by these into the sesamoid bones at the base of the proximal phalanx of the hallux. The 

 tibial insertion is associated with that of the abductor hallucis, and the fibular with that 

 of the plantar part of the adductor hallucis. 



The dorsal layer (fig. 6, d 1 to c7 6 ). — This group includes (1) the abductor hallucis ; 



(ZOOL. CHALL. EXP. — PART XVI. — 1882.) Q 8 



