REPORT ON THE MARSUPIALIA. 113 



vast amount of information which, has already been furnished upon the anatomy of this 

 order rendered further investigations on my part unnecessary. Professor Bischoff 1 of 

 Munich, who is perhaps the greatest living authority upon the structure of the Ape, and 

 its relation to that of Man, has added greatly to our knowledge in this respect, and so 

 also have Huxley, 2 Duvernoy, 3 Vrolik, 4 Halford/' Macalister, 6 Champenys, 7 Euge, s 

 Murie and Mivart, 9 and many others. Except in the case of the three specimens, above 

 quoted, the following facts are borrowed from the writings of these distinguished authors. 



I have found the memoirs mentioned below especially useful in the present research. 

 I regret, however, that I have not had an opportunity of studying Professor Halford's 

 papers, and have thus been obliged to trust for my information regarding them to other 

 memoirs in wdiich they are noticed. 



Plantar layer. — In the Quadrumana the adducting apparatus of the digits is usually 

 very powerful, and further, it is plantar in position. Owing to the wide range of 

 movement which is possessed by the opposable hallux, the adductor hallucis is developed 

 to an extent far beyond the adductors of the other toes. It is in this group of animals 

 that we observe for the first time a decided tendency in this muscle to split up into 

 two parts, viz., an adductor obliquus hallucis, and an adductor transversus hallucis 

 (i.e., the transversalis pedis). Throughout Mammalia we occasionally see traces of a 

 transverse adductor in connection with one or other of the muscles belonging to the 

 plantar layer, but these are few in number, and the instances in which they occur have 

 little direct bearing upon each other. In the Tamandua, Sloth, Elephant, and apparently 

 also in the Armadillo, a transverse adductor of the index has been observed ; again, in 

 the Walrus a transverse adductor hallucis is present, and as we have noted, both Meckel 

 and Ruge also consider the adductor hallucis in the Virginian Opossum to be double. 



Bischoff in his memoir upon the Hylobates leuciscus gives an admirable account of 

 the adductor hallucis in a great number of Apes. He shows that in the Gorilla, Hylobates 

 leuciscus, 10 Cynoceplialus maimon, Cercopiihecus sabdus, and Macacus cynomolgus the 

 two heads of this muscle are present as separate and distinct elements, whilst in the Orang, 11 



1 Beitrage zur Anatomie des Hylobates leuciscus, Miinchen, 1870 ; Beitrage zur Anatomie des Gorilla, Miinchen, 1879. 



2 Structure and Clarification of Mammalia (Lectures delivered before the Royal College of Surgeons), Medical 

 Times and Gazette, 1864. 



3 Des caracteres anatomiques des grands singes pseudo-anthroponiorphes, Archives du Museum, torn. viii. 



4 Recherches dAnatomie sur le Chimpanse, 1841. 



5 Not like Man, Bimanous, and Biped, nor yet Quadrumanous, but Cheiropodous, Melbourne, 18G3 ; Lines of 

 Demarcation between Man, Gorilla, and Macaque. Melbourne, 1864. 



6 Article on the Gorilla, Proc. Roy. Irish Academy, voL i., ser. ii. pp. 501 and 5<>4. 



7 On the Muscles and Nerves of a Chimpanzee and a Cynoceplialus anubis, Journal of Anatomy and Physiology, 

 vol. vi. pp. 187 and 203. 



8 Zur vergleichenden Anatomie der tiefen Muskeln in der Fussohle, Morph. Jalir., 1880. 



9 Anatomy of the Lemuioidea, Transactions of the Zoological Society, vol. xii. 



10 In the text (p. 39) the author states that in Hylobates the two muscles are coalesced, whilst in the table at the 

 end of the work he says that they are " beide getrennt und stark." 



ii Bischoff asserts that the two heads are separate. Ruge, however, figures the muscle as a single fleshy mass (fig. 54). 

 (ZOOL. CHALL. EXP. — PART XIV. — 1882.) Q 15 



