1903.] THE MUSCLES OF THE UNGULATA. 283 



Plantar JRegion, 



Flexor hrevis digitoruvi pedis. — This rudimentary structure 

 has already been described with the plantaris, of which it is the 

 continuation into the sole. 



The Accessorius is always absent, the only approach to it is a 

 small fleshy bundle seen by Mivart and Murie in Hyrax and by 

 ourselves in the Ox (40). 



Deep Plantar Muscles. — In the Hippopotamus (1, 3) there is 

 an abductor indicis, an abductor minimi digiti, and double-headed 

 flexores breves for each toe. 



In the Suidss there is a greater suppression and evidently con- 

 siderable individual variation. Lesbres (Y.) describes only a few 

 fleshy fibres on the outer and inner side of the foot, while 

 Ohauveau (II.) says that four interossei are present. In our 

 specimen of Red River-Hog (11) we found one interosseus going 

 to the tibial side of the medius, one to the fibular side of the 

 annularis, and one to each side of the minimus, in addition to 

 a feeble abductor minimi digiti. In the Peccary (14), on the 

 other hand, there were only three muscles, that to the tibial side 

 of the minimus being absent. In the rest of the Artiodactyla it 

 is usual to find only two double-headed flexores breves, each head 

 having a sesamoid bone developed in it ; there are, however, no 

 fleshy fibres in these structures. An exception is the Water- 

 Chevrotain, in which Chatin (XI.) describes four interossei, and 

 from his figure there appears to be a double-headed fleshy flexor 

 brevis to each toe. The increased development is not surprising 

 when one remembers how large the lateral digits are in this 

 animal. In the Tapir (61) we found a double flexor brevis to 

 each toe, and Murie (XVII.) agrees with this but describes in 

 addition two superficial muscles to the medius. In the Horse two 

 tinterossei {sic) are described by Ohauveau (II.) and Cunningham. 



Among the Subungulata the sole-muscles are more numerous ; 

 Hyrax (75) has an adductor indicis and annularis on a sviperficial 

 plane and deep to them three double flexores breves, while in 

 addition to these there is an abductor indicis and quarti digiti. 

 In Mivart and Murie's specimen all these were present as well as 

 an adductor medii on the superficial plane. 



In the Elephant (85), Paterson and Dun found an abductor 

 hallucis rising fi'om the calcaneum, and a " flexor brevis digiti 

 secundi," which comes from the tuber calcis and covers the long 

 tendons entering the sole. There is some reason to think that this 

 represents the flexor brevis digitorum of Man, saA^e that its 

 insertion is into the metatarso-phalangeal capsule instead of into 

 the middle phalanx. The minimus has an abductor and a double- 

 headed flexor brevis. The four interosseous spaces are well sup- 

 plied with muscles which do not seem to be arranged as double- 

 headed flexores breves. Without an accurate diagram it is 

 difiicult to say whether any of these belong to the more super- 

 ficial adductor series of the mammalian foot, or whether they are 



