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



A few fibres of the adductor minimi digiti go to the radial margin of the metacarpal 

 bone of this digit, and on this account it has been described as the opponens minimi 

 digiti by veterinary anatomists. 



But this description of the muscles of the hand of the Dingo does not agree with that 

 given by Chauveau l of the same muscles in the domestic Dog. This author describes a 

 flexor brevis pollicis, and speaks of an opponens pollicis and an opponens minimi digiti. 

 The two latter are the representatives of the adductors of these fingers in man. Further, 

 the muscle which he designates the adductor minimi digiti is in reality the abductor. 

 Lastly, he looks upon the partially fused intermediary muscles and the dorsal interossei 

 as composing a single series of muscles which he calls the metacarpal interossei. 



The arrangement of the hand muscles in the Cat seems to be very simdar to that in 

 the Dog. Strauss-Durckheim, in his elaborate work upon the Anatomy of the Cat, gives 

 a very careful account of these muscles. It is unfortunate that he has chosen for them 

 a mode of nomenclature which renders his descriptions very obscure. He discards the 

 term interossei, and calls all the intrinsic muscles of the hand adductors or abductors, 

 according as they draw the digits towards or away from the middle line of the body. 

 This leads to confusion, and it is only by a reference to his magnificent plates that his 

 meaning can be clearly made out. He distinguishes three kinds of abductors and 

 adductors, viz., short, middle, and long, according as they are inserted into the sesamoid 

 bone, the base of the first phalanx or the second phalanx through the inediuru of the 

 extensor tendon. 



The above account of the intrinsic muscles of the manus was published in the form 

 of an abstract in the Journal of Anatomy and Physiology (vol. xii.). Since then Dr. A. 

 H. Young has greatly supplemented our knowledge of these muscles in the Marsupialia 

 by describing them in five different species, viz., in the Opossum, the Wallaby, the 

 Yellow-footed Eock Kangaroo, and the Wombat (Jour. Anat. and Phys., vol. xiv.), and 

 still more recently in the Koala (Jour. Anat. and Phys., vol. xvi.). In all of these the 

 arrangement of the intrinsic muscles is trilaminar. 



The homologies of the intrinsic muscles will be fully discussed when we consider the 

 corresponding muscles of the foot. 



The Nerves of the Fore Limb of the Thylacine and Cuscus. 



Swan, in his work upon the Comparative Anatomy of the Nervous System (p. 193), 

 justly remarks that, as a general rule, the number of nerves entering into the composition 

 of the brachial plexus in Mammalia is greatly influenced by the length of the neck. The 

 number of vertebrae being, as a rule, the same, it follows that, when the neck is a lengthy 

 one, the nerves are placed at greater intervals from each other, and in consequence of 



1 Comparative Anatomy. 



