REPORT ON THE MARSUPIALIA. 83 



of the fifth metatarsal bone. The close association of this muscle, with the abductor ossis 

 metatarsi minimi digiti seems to indicate that it is a development from the latter. Murie, 

 however, points out with truth that if the fibrous structures into which it is inserted be 

 raised (artificially) from the base of the fifth metatarsal, it passes uninterruptedly into 

 the fleshy belly of the outer head of the flexor brevis minimi digiti — the two thus 

 forming a digastric muscle. Upon these grounds he classes it with the short flexor of the 

 minimus. 



I am confirmed, however, in my opinion that this muscle is a third abductor of the 

 minimus (which as we have seen is by no means an unusual occurrence) by a study of the 

 corresponding muscle as exhibited in Dr. Murie's drawing of the intrinsic pedal muscles of 

 Otaria jubata (Trans. Zool. Soc, vol. vii. pi. Lxiii. fig. 38). In this animal the muscle gains 

 an independent insertion into the outer side of the base of the first phalanx of the minimus. 

 Dr. Murie terms it, " flexor brevis minimi digiti." Both heads of the short flexor, 

 however, arc likewise present, and these he names the " fifth double interosseus." 



The second muscular bundle is very deeply placed, and lies obliquely in the sole 

 {f x t). It arises from the plantar surface of the middle cuneiform bone and tapering 

 as it proceeds inwards joins the rounded tendon of the abductor hallucis about an inch 

 and half from its origin. This muscle is evidently the inner head of the flexor brevis 

 hallucis, displaced from its neighbour. Dr. Murie's account is somewhat different. He 

 says, " The two short extra and deeply situated muscles met with in the sole of Otaria 

 jubata are exactly similar in appearance and situation in Trichechus rosmarus. From 

 position and attachments, though covered (and, indeed, entirely hidden), by the deep plantar 

 fascia, they nevertheless may be the homologues of a double adductor hallucis, though 

 it is still more likely that the tibial division is a flexor brevis hallucis, and the fibular one 

 above an adductor." I cannot agree with Dr. Murie, in regarding either of these muscles 

 as the adductor hallucis. The nerve supply shows this, if indeed any other evidence is 

 necessary, beyond the presence of the true and undoubted adductor itself. In my 

 specimen the muscle in question was single and supplied by the internal plantar nerve. 

 Both slips I believe should be associated with the abductor hallucis, and inner head of 

 the flexor brevis hallucis. 



Nervous arrangements. — The abductor ossis metatarsi minimi digiti, and the muscular 

 slip associated with it receive their nerve twigs from the trunk of the external plantar 

 nerve (e.p.n.). The abductor minimi digiti is supplied by a branch from the superficial 

 division of this nerve (s.). The deep division (d.) of the external plantar turns inwards 

 under cover of the fibrous adductor minimi digiti and the adductor hallucis, and gi\< - 

 branches to all the intrinsic muscles, with the exception of the flexor brevis and the 

 abductor hallucis. It ends in the substance of the inner head of the flexor brevis 

 indicis. The outer head of the flexor brevis hallucis, the abductor hallucis, and the small 

 deep belly representing the inner head of the flexor brevis hallucis are supplied by twigs 



