1899.] THE MYOLOGY OF THE EDE>-TATA. 1005 



radial ossicle, or so-called pre-pollex. In Tamandua (14, 15) the 

 muscle is absent. Among the Basypodidce the plantaris rites from 

 the ridge above the external condyle in Dasypus {22, 23), and is 

 continued into the sole of the foot, 'where it flattens out and sends 

 slips to three or four of the digits, which slips are perforated by 

 the tendons of the flexor longus digitorum. In Tatusia (25) there 

 is no separate plantaris. In Chlamydo2)1wrns (27, 28, 28 a) the 

 tendon passes into the sole of the foot, where it divides into four 

 slips. In tlie Manidce (29, 32, 33, 34) there is no separate 

 plantaris, it is probably fused with the very large external head of 

 the gastrocnemius. In the Orycteropod'idce (35, 36, 37) the 

 generalized mammalian arrangement is found ; the plantaris passes 

 under the tuberosity of the calcaneum, and forms a fibrous flexor 

 breA'is digitorum for the four outer digits. 



Flexor brevis digitorum. — In the Bradypodidce (1, 2, 5, 9, 10), 

 Myrmecophayidce (11, 14, 15, 17), and Manidce (29, 32), the muscle 

 rises from the posterior part of the lower surface of the calcaneum, 

 and has no connection with the plantaris when that muscle is 

 present. The insertion is into the three middle or four outer 

 digits. The tendons are usually inserted into those of the flexor 

 longus, instead of being perforated by the latter. The information, 

 however, as to the manner of ending of these tendons is very 

 scanty. ^In the Dasyi^odidoi (22, 23, 27, 28) and Orycteropodidce 

 (35, 36, 37) the flexor brevis is a continuation of the plantaris, as 

 in most generalized mammals. 



Flexores tibialis et fibidaris. — In the Bradypodidne these two 

 muscles are difficult to distinguish : in any case they coalesce 

 before reaching the ankle, and then divide into three tendons, which 

 pass to the second, third, and fourth toes respectively. This 

 applies to Bradypus (1, 2, 5) and Cliolcepus (8, 9, 10). In some 

 records oi Bradypus (2, 5) a femoral head is also recorded, but a 

 consideration of the conditions has decided us to regard this as a 

 plantaris. Among the Myrmecopliayidce the two muscles are 

 practically inseparable ; they form a single flat tendon, which in 

 Myrmecophaya (12) and Tamandua (15) has a sesamoid body 

 where it passes into the sole of the foot. In Tamamhia (14, 15) 

 tendons pass to all five toes, but in CydotJmrus (17, 19, 20) there 

 is no slip for the hallux. In the Dasypodidct' (22, 23, 25) the 

 tibial and fibular heads unite in the lower part of the leo' and are 

 inserted into a very large sesamoid bone in the sole of the foot, 

 which is held in place by a fibrous band from the calcaneum, the 

 equivalent of the accessorius. From the front of the sesamoid 

 bone five tendons pass to the terminal phalanges of the five digits. 

 In Chlamydophorus (27) the sesamoid bone was replaced by a 

 cartilaginous nodule. In the Manidce {22, 23, 25) the two muscles 

 are much more distinct, the flexor fibularis forming a very lar^e 

 tendon into the inner side of \\hich the small tendon of the flexor 

 tibialis is inserted. There are tendons for the four outer toes, 

 but none for the hallux. In the Oryc/erojjodidce (35, 36) the 

 flexores tibialis et fibularis fuse in the leg and from the tendnn 

 Proc. ZooL. Soc— 1899, No.LXY. 65 



