REPORT ON THE MARSUPIALTA. 73 



the tendon of the flexor longus digitorum. In the sole it gives twigs to the flexor brevis 

 digitorum, and then breaks up into cutaneous branches for the digits and web. These 

 supply both sides of the hallux, of the index, and of the medius, and also the tibial side 

 of the annularis. The external plantar nerve reaches the foot by passing over the outer 

 side of the os calcis. Upon the fibular margin of the pes it divides into a minute superficial 

 twig for the outer side of the minimus, and a large deep branch. Before dividing, the 

 nerve trunk gives twigs to the abductor ossis metatarsi minimi digiti, the outermost belly 

 of the flexor brevis digitorum, and the accessorius. The deep division turns inwards under 

 cover of the superficial and deep flexors of the toes, and insinuating itself between the 

 plantar and intermediate muscles divides into a large cutaneous and a small muscular 

 part. The cutaneous nerve emerges at the lower border of the adductor minimi digiti 

 and bifurcates to supply the adjacent sides of the minimus and annularis, whilst the 

 muscular branch continues inwards under cover of the adducting muscles as far as the 

 metatarsal of the index, where it breaks up into its terminal filaments. It supplies 

 all the intrinsic muscles, with the exception of the abductor ossis metatarsi minimi 

 digiti, which receives its nerve direct from the trunk of the external plantar, and 

 the flexor brevis hallucis, which is probably supplied by the internal plantar nerve, 

 although it is right to state that I have been unable to trace any nervous filament to this 

 muscle. 



A passage in Meckel's work upon Comparative Anatomy regarding the interossei in 

 the pes of the Ormthorhynchus led me also to examine the corresponding muscles in the 

 hand of this animal. He says : — " Dans l'ornithorhynchque, ils se comportent absolument 

 de la meme maniere cme les interosseux de la main ; a cela pres qu'ils sont plus minces 

 et plus greles." I found the arrangement very different. Thus the plantar layer is only 

 represented by a single minute thread-like muscle — the adductor minimi digiti. The 

 dorsal interossei are also absent, but, in the intermetatarsal spaces, strands of tough fibrous 

 tissue exist, and these may represent them. The intermediate flexores breves are well 

 marked, each being composed of two fleshy slips with the exception of that for the 

 minimus, which has only an inner or ulnar head. 



Echidna setosa (PI. IX. fig. G). 



The foot of the Echidna is pentadactylous, powerful, and somewhat peculiar in 

 its form. The hallux is exceedingly short and stunted, and is provided with a short 

 rounded nad which covers the entire dorsal surface of the digit. The index is con- 

 siderably longer than the other toes, and is armed with a remarkably long curved 

 claw. The succeeding digits gradually diminish in size as we proceed towards the 

 minimus, and each is furnished with a claw similar in shape to that of the index, but of 

 a size proportionate to that of the digit to which it belongs. The intrinsic muscles of 

 this foot are very weakly developed, and many are absent. The stunted hallux is 



(ZOOL. C1IALL. EXP. — PART XVI. — 1882.) Q 10 



