EEPORT ON THE MAESUPIALIA. 119 



the second and third are inserted one upon either side of the base of the first phalanx of 

 the medius ; and the fourth is inserted upon the outer side of the base of the first phalanx 

 of the annularis. The two exceptions to this rule are — (l) the Gorilla, and (2) the 

 Lemur. 



Bischoff l has recently shown that in the Gorilla the pedal dorsal interossei are 

 arranged in the same manner as in the human foot, viz., with reference to a line drawn 

 through the index or second toe. Duvernoy 2 and Macalister, 3 however, differ from 

 Bischoff upon this point, and consider the foot of the Gorilla no exception to the general 

 rule, and therefore it is possible that the disposition of these muscles in this animal 

 may vary. 



In the Lemur I find that the dorsal interossei are arranged with reference to a fine 

 drawn through the annularis. The first is inserted upon the inner side of the base of 

 the index ; the second upon the same side of the base of the medius ; and the third and 

 fourth upon either side of the base of the annularis. This is very evident when these 

 muscles are dissected from the dorsal aspect of the foot. 4 In the manus the dorsal inter- 

 ossei are arranged upon the same plan. Duvernoy considers the peculiarity of arrange- 

 ment in the human foot to be due to the fact that the index which constitutes the centre 

 for the movements of abduction and adduction is the longest of the toes. It is interesting 

 to note in connection with this that the annularis is the longest digit in the foot of the 

 Lemur. In the Gorilla, on the other hand, the medius is the longest toe. 



BlMANA. 



We must now endeavour to determine the relation which exists between the intrinsic 

 muscles of the human foot, and those of the feet of the lower animals. There is no 

 difficulty in recognising the members of the dorsal layer. They are — 



1. The abductor hallucis. 



2. The abductor minimi digiti. 



3. The occasional abductor ossia metatarsi minimi digiti. 



4. The four dorsal interossei. 



The plantar layer is represented by (1) the adductor hallucis, and (2) the transver- 



1 Beitrage zur Anatoniie des Gorilla — Aus den Abhandlungen der K. bayer Akademie der W. II., clxiii. 

 Bd. iii. Abth. 



2 Lot. tit. 3 Lot. tit. 



* This is very clearly and beautifully represented in plate lxxv. (figs. 1 and 2) of the Atlas (vol. ix.), which 

 accompanies the text (vol. vi.) of the great work which has recently appeared entitled " Histoire Physique, Naturelle et 

 Politique de Madagascar," by M.M. Alph. Milne-Edwards and Alfred Grandidier. In the text of vol. vi. which is 

 devoted to the Lemurs, reference is made in page 191 to this disposition of the dorsal interossei, but the authors hardly 

 seem to have realised its full importance. They say : — "Dans l'intervalle qui separe le troisieme metatarsien du 

 quatrieme, et celui-ci du cinquienie orteil existent deux interosseux dorsaux qui se fixent de chaque cute de la 

 premiere phalange du quatrieme orteil." In the case of the manus it is neither figured nor described. 



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VA 



