402 MR. ST. GEORGE MIVART AND DR. J. MURIE [Julie 26, 



The flexor carpii ulnaris is but moderately large ; it arises from 

 the ulnar aspect of the olecranon, and for a very short distance from 

 the back of the shaft of the ulna. Its tendon, which is broad and 

 flat, commences about halfway down the forearm, and has an in- 

 sertion into the pisiform bone (fig. 2, F. c. u.). 



In the Hare and Rabbit this muscle has likewise a slip of origin 

 from the inner condyle in common with the flexor sublimis and pro- 

 fundus. 



The Guinea-pig has this muscle relatively larger in the belly than 

 the Agouti ; its origin and insertion are similar. 



Palmaris brevis (fig. 2, P. b.). This muscle, so diminutive in 

 Man and the higher Quadrumana, is in Dasyprocta cristata very 

 remarkable by reason of its great strength, and also from there being 

 a very large palmar ossicle so developed as almost to divide it into two 

 portions. The muscular fibres stretch across, taking origin from the 

 first and the fifth digits for the whole length of the metacarpals. 



The ossicle (fig. 2, P.o.) is nearly as long as the rather diminu- 

 tive pollex, its proximal attachment being to the trapezium and base 

 of the pollex ; it looks, in fact, like an extra digit laid obliquely across 

 the palm. The distal extremity reaches to the middle of the palm, 

 but points towards the fifth digit ; it terminates anteriorly in a some- 

 what sharp-pointed cartilaginous apex, its base alone being osseous. 



In the Rabbit there is a double palmar cartilage, approaching in 

 shape to the ossicle in the Agouti, not attached to the sides of the 

 palm by muscular fibre as in Agouti, but only by a tendinous fascia. 



In the Hare we find no ossicle or cartilage, but only a strong fascia. 



In the Guinea-pig there is a palmar ossicle very nearly corre- 

 sponding to that described in the Agouti, but the muscular fibres 

 on either side are much paler and fewer in number. 



Under the head of flexor brevis m anus we may mention a small 

 muscular mass superficial to the flexor tendons. The median nerve 

 distributed to the palmar surface of the manus is closely embraced 

 and surrounded by this muscle, which arises from the surface of the 

 deep tendons on either side of the middle line, and has an apparent 

 attachment or insertion into the proximal end of the fifth digit. 



This muscle evidently agrees more or less with what we found in 

 the Hyrax* — with this difference, however, that in the latter it 

 ended in three tendons. 



What Prof. Huxley has described f as a separate belly of muscle 

 proceeding from the tendons of the flexor sublimis in the Rabbit may 

 be the representative of this muscle, with but a single tendon, going 

 to the fifth digit. 



In the Guinea-pig we failed to detect any such structure. 



In the Hare this muscle is wanting. 



All that we noticed as representing the Palmaris Jongus was a 

 small slip adherent upon the voluminous flexor sublimis. This slip 

 arises from the internal condyle, and seems to be continued into the 

 palm of the hand by the superficial fascia. 



There is a similar diminutive tendon in the Rabbit ; but in the 

 * P. Z. S. 1865, p. 341. t Himtcrian Lectures, 1865. 



