REPORT ON THE MARSUPIALIA. 87 



The intrinsic muscles of the foot in Tamandua derive their nerve supply in the usual 

 manner, viz., the abductor hallucis and flexor brevis hallucis from the internal plantar 

 nerve, and the other muscles from the external plantar nerve. The deep division of the 

 external plantar nerve traverses the sole, between the plantar and intermediate layers of 

 muscles (fig. 5, e.p.».). 



Dasypus sexcinctus (PI. VIII. fig. 3). 



The foot of this animal is of peculiar interest from the fact that, except in the case of 

 the hallux and minimus, the intermediate flexors and the dorsal abductors have undergone 

 regression, and are converted into fibrous tissue. 



The plantar layer is web! represented. It consists of four muscles, viz. : — 



1. The adductor hallucis (p 1 ). 



2. The adductor indicis (p 2 ). 



3. The adductor annularis (p 4 ). 



4. The adductor minimi digiti (p 5 ). 



These are inserted so as to adduct the toes towards a line drawn through the medius. 

 The first three arise by a common origin from the fibrous textures at the bases of the 

 second and third metatarsal bones, and from this they diverge so as to reach their 

 respective insertions. The adductor indicis has an additional head of origin from the base 

 of the third metatarsal in common with the origin of the adductor annularis. Tbis may 

 represent a transversus indicis. 



Intermediate layer.— Only two members of the intermediate group are present, viz., 

 the flexor brevis hallucis (f 1 / and t), and the flexor brevis minimi digiti (f 5 ). 



The flexor brevis hallucis is well developed, and has the usual bicipital character. 

 The tibial head (fH) is, however, to a certain extent fused with the abductor hallucis (d 1 ), 

 and takes origin by a common tendon with this muscle, far back in the sole, from the 

 ligaments in connection with the os calcis and astragalus. The outer or fibular head 

 springs from the plantar surface of the ento-cuneiform, and both slips are inserted into the 

 sesamoid bones at the base of the hallux. 



The flexor brevis minimi digiti (/ 5 ) is an exceedingly minute slip of muscular fibres, 

 and can have little or no action upon the digit into which it is inserted. 



The dorsal layer is composed of three muscles, viz., the abductor hallucis (d), the 

 abductor minimi digiti (d), and the abductor ossis metatarsi minimi digiti (o.m.). 



The abductor hallucis, as we have seen, to a certain extent fuses with the tibial head 

 of the flexor brevis, and they both have a common origin from the astragalus and os calcis. 

 They soon separate, however, and the abductor is inserted by a long narrow tendon into 

 the tibial side of the ungual phalanx of the hallux. 



The abductor minimi digiti and abductor ossis metatarsi arise from the os calcis. The 



