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



former is inserted by a long tendon into the fibular side of the distal phalanx of the 

 minimus, whilst the latter is inserted into the base of the metatarsal bone of the same 

 digit. 



But the most remarkable feature in the pes of the Dasypus sexcinctus is that the place 

 of the absent muscles is taken by fibrous bands (f.b.) which have precisely the same dis- 

 position and connections as those muscles of which they are the substitutes. These fibrous 

 bands represent the fused flexores breves and dorsal interossei, and it is difficult to ascribe 

 to them any function unless they act by preventing over-extension at the metatarso- 

 phalangeal joints. The outer head of the flexor brevis indicis is not entirely transformed 

 into fibrous tissue. Lying along its deep margin a fleshy slip of considerable size may 

 be detected. From the manner in which the digits are bound together, they can have 

 little power of independent movement, and this, no doubt, is the reason of the transforma- 

 tion of these intrinsic muscles into fibrous bands. 



A very accurate account of the myology of the pes of this animal may be found in an 

 able memoir by Mr. J. C. Galton. 1 I cannot agree with Mr. Galton, however, in the 

 terms which he has applied to certain of the muscles. He looks upon the muscle which 

 stretches between the os calcis and the base of the fifth metatarsal bone as being the 

 abductor minimi digiti, and the muscle passing from the os calcis to the ungual phalanx 

 of the minimus as being the flexor brevis. There can be little doubt that these muscles 

 represent those after which I have named them, viz., the abductor ossis metatarsi and the 

 abductor minimi digiti. The minute fasciculus (to which, by the way, he has affixed no 

 name) appears to me to be the true flexor brevis minimi digiti. 



But, again, he is of opinion that the adductor minimi digiti is the opponens. Such a 

 conclusion I consider to be altogether untenable, as it is the very essence of an opponens 

 that it should be inserted into the metatarsal bone, whilst this muscle is inserted into the 

 distal phalanx. 



The only discrepancies which exist between the above description of the intrinsic 

 muscles in the foot of Dasypus and that given by Mr. Galton are : (1) he takes no notice 

 of the fibular head of the flexor brevis hallucis which was very apparent in my specimen ; 

 and (2) he mentions an " interosseous " muscle going to the tibial side of the root of the 

 index. This muscle was only present in the form of a fibrous band in the Armadillo I 

 dissected, and it apparently represents the first dorsal interosseous muscle fused with 

 the tibial head of the flexor brevis indicis. 



Professor Macalister 2 mentions two muscles in Dasypus which in my specimen were 

 merely represented by fibrous bands, viz., an abductor indicis or first dorsal interosseous 

 muscle, and an abductor annularis or fourth dorsal interosseous muscle. It is a point of 



1 Linnean Transactions, vol. xxvi. pp. 562 and 563. 



2 Anatomy of Chlamydophorus truncatus, with notes on the structure of other species of Edentata, Transactions of 

 the Royal Irish Academy, vol. xxv. p. 253. 



