112 THE VOYAGE OF H.M.S. CHALLENGER. 



The internal plantar nerve (i.p.n) on entering the sole at once breaks up into four 

 digital branches : — These are distributed as follows : — (1) the innermost goes to the inner 

 side of the hallux and gives three minute twigs to the large inner head of the flexor brevis 

 hallucis ; (2) the next divides to supply the adjoining margins of the hallux and index, 

 and gives a muscular twig to the first lumbrical ; (3) the third bifurcates and supplies 

 the adjacent borders of the index and meclius, and furnishes a filament to the second 

 lumbrical ; (4) the fourth in like manner supplies the contiguous sides of the medius and 

 annularis, and gives a twig to the third lumbrical. From the trunk of the internal 

 plantar, before it breaks up into its digital branches, a few filaments are furnished to 

 the flexor brevis digitorum. 



The external plantar nerve (e.p.n) turns outwards under cover of the flexor brevis 

 digitorum, and after supplying the abductor ossis metatarsi minimi digiti with one or 

 two twigs divides into its superficial and deep divisions. The superficial part ends in 

 two digital branches, of which one goes to the outer side of the minimus, whilst the 

 other bifurcates to supply the adjacent borders of the minimus and annularis. The 

 latter gives a twig to the fourth lumbrical which enters its plantar surface, and it is to 

 be noted that in passing to its distribution it lies superficial to the flexor tendons and 

 lumbricals. The deep part of the nerve turns inwards upon the flexores breves and 

 under cover of the adductors, and reaching the inner margin of the sole it ends in 

 the substance of the outer head of the flexor brevis hallucis. In addition to this, it 

 supjxlies twigs to the adductors and to both heads of each of the four outer flexores 

 breves. 



There are two points in which this arrangement of the nerves is peculiar, viz. : (1) in 

 the two outer lumbricals receiving their nerve supply upon their superficial aspect, and 

 in the nerve to the third coming from the internal plantar ; (2) in the outer head of the 

 flexor brevis hallucis receiving its nerve supply from the deep part of the external 

 plantar. 



I am quite aware that it may be objected that this muscle is not the outer head of 

 the flexor brevis hallucis, but the oblique adductor hallucis. In answer to this I can 

 only state that the muscular slip in question lies in series with the other flexores breves ; 

 that in fact it is a flexor brevis in every respect except its peculiar nerve supply. It is 

 further to be remembered that a large fan-shaped adductor hallucis is present, superficial 

 to the short flexores (p 1 ). 



QuADRUMANA. 



Of this order of Mammalia I have only examined the feet of a Lemur, of a New T 

 Guinea Baboon (Cynecophalus sphinx), and of a large Monkey of which I merely 

 possessed the partially skinned foot, and therefore could not determine with certainty 

 the species. I believe, however, that it had been taken from a specimen of Atcles. The 



