1899.J IHE MYOLOGY OF THE EDEXTATA. 335 



phagidce the arrangement closely resembles tbat of the Sloths. Of 

 three specimens of Mynnecophaga the muscle was bilaminar in 

 two (12, 13), the superficial part going to the fascia and posterior 

 annular ligament and the deep to the styloid process of the radius. 

 In Tamandua (14, 16) and Cijdothurus (17, 18, 19, 20, 21) the 

 same condition obtained. It is well figured by Cuvier and Lauril- 

 lard (plate 237). In the Dasypodidctf the supinator longus is absent 

 in Dasypus {2'2, 23, 24), Tatusia (25, 26), and Cldamydoijliorus 

 (27, 28). In the Manidte the muscle may be present (32, 33, 34) 

 or absent (29, 30, 3J). AVhen it is present it is closely connected 

 at its origin with the deltoid, so much so that by some observers 

 the two muscles have been described as continuous. In Orycieropius 

 the muscle is present (35, 36, 37) and rises from a considerable 

 portion of the length of the humerus. It is inserted partly into 

 the radius, partly into the fascia over the tendons. 



Extensoi'es carpi radiules lonyior e.t brevior. — In the Sloths there 

 are usuall}' two insertions, although the muscular belly is described 

 as single. In three specimens of Bradypiis (2, 3, 4) the muscle, 

 described as single, ended in two tendons, which were inserted into 

 the radial pair of the three metacarpals ; but in our own specimen 

 (i.) the longior was absent and the bre\ior passed from the external 

 condyle to the middle of the shaft of the central (3rd) metacarpal 

 bone. Mackintosh's specimen (5) appears to have presented an 

 identical arrangement. In three specimens of Cliolcepus (8, 9, 10), 

 in spite of the presence of only two metacarpal bones, both tendons 

 were present, and in our own. (8) we noticed that the muscular 

 bellies were separable and that the longior was the smaller of the 

 t«o. The two tendons w-ere in all three cases inserted into the 

 radial of the two metacarpals. The Myrmecophagidxe are re- 

 markable for the suppression of the extensor carpi radialis longior, 

 but the brevior is unusually strong. In Myrmecophaga {11, 12, 

 13), Tamandua (14, 15), and Cyclothurus (17, 18, 20) only the 

 brevior was present, but in another specimen of the latter aninjal 

 (19) both muscles were found. In the Dasypodidie both muscles 

 seem to be usually present, though the two bellies are sometimes 

 described as being fused. The Manidce are remarkable for the 

 absence of the longior, this condition being noticed in five speci- 

 mens (29, 30, 31, 32, 33). In M. javanica, however, tendons are 

 described as passing to the second and third metacarpals. In 

 Orycteropus the longior seems to have been present in (35) and 

 absent in (36). 



Extensor communis digitorum. — This rises as usual from the 

 external condyle and is inserted into a variable number of digits. 

 In ClioJoepnis it always passes to the second and third, the only two 

 which are present. In Bradypjus it may go to all three digits (1, 

 5, 6), the two outer (3) or the two inner (4). In Myrmecophaga 

 all the digits may be provided \^ith tendons (12, 13) or only the 

 third and fourth (11). In Tamandua (14, 15) slips go to the 

 medius and annularis only. Cyclothurus (17, 18, 19, 20, 21) 

 possesses only a tendon for the medius. Basyjms (22, 23, 24), 



