PRIMROSE : THE ANATOMY OF THE ORANG OUTANG 
71 
the outer head of the flexor brevis has already been alluded to. Re- 
garding the development of the transverse and the oblique adductor. 
Bischofif states that in the Gorilla, the Orang, Cynocephalus and 
Cercopithecia, both muscles are strongly developed and are separate 
from one another, whilst in the Chimpanzee, Gibbon, Pithecia and 
Hapale they are both present but united. In Macacus they are both 
present but weak. 
The Abductor minimi digiti arose from the under aspect of the os 
calcis by two heads, one from the inner and one from the outer aspect of 
the bone, the inner head passing on the deep aspect of the flexor brevis 
digitorum. The muscle is also intimately united to the tendon of the 
peroneus brevis in the sole, from which it may be said to have an 
additional origin. This muscle terminated in a long tendinous structure 
which was inserted with the dorsal extensor expansion over the base of 
the proximal phalanx, and was attached also to the outer aspect of the 
proximal phalanx. 
The Abductor ossis metacarpi quinti referred to on page lo, is closely 
associated with the abductor minimi digiti. It arose from the under 
aspect of the os calcis in common with the outer part of the flexor brevis 
digitorum and immediately overlying the inner head of the abductor 
minimi digiti. This structure is almost wholly tendinous in character. 
It was inserted into the outer and under aspect of the base of the fifth 
metatarsal bone. 
The Flexor brevis minhni digiti arose from the base of the fifth meta- 
tarsal bone, and was inserted into the outer aspect of the base of the 
proximal phalanx. Rudolf on the right side found a slip of origin from 
the cuboid. 
The Opponens minimi digiti arose from the sheath of the peroneus lon- 
gus, and was inserted into the whole length of the fifth metatarsal bone 
along its outer aspect. The muscle was not found by Pick in the 
Orang. Bischoff^ found it in the Gorilla. 
The Interossei correspond in their detailed description to those of the 
hand. The third digit possessed two dorsal interossei lying in the inter- 
osseous spaces between the second and third and the third and fourth 
metatarsal bones. They arose from the dorsal surface and lateral 
margins of the two adjacent metatarsals ; but, in addition, each is joined 
by a fleshy belly arising from the plantar and lateral aspects of the third 
metatarsal bone, the fleshy bellies of the two muscles meeting in the 
plantar aspect of the bone. Thus the third metatarsal bone is com- 
I Loc. cit. 2, p. 32. 
