PRIMROSE : THE ANATOMY OF THE ORANG OUTANG 
67 
noted a contribution similar to that I have described above in my 
Orang. He observed a remarkable deviation from the human type in 
Cynopithecinae where the flexor brevis pedis arose partly from the tendon 
of the plantaris (where this passes over the pulley-like hinder extremity 
of the calcaneum, to end in the plantar fascia) and partly from the long 
flexor tendons, so that it completely lost its connection with the os 
calcisd Again, Turner^ observed in man that the tendon of the short 
flexor for the little toe in one case arose from the common flexor 
tendon previous to the sub-division of that structure. Similar com- 
munications between the short and long flexors have been recorded in 
the apes by Bischoff.^ Regarding variations in origin in man it may 
be noted that the flexor brevis sometimes arises from the cuboid bone, 
the cuneiform bones, or the bases of the metatarsal bones (Testut). 
The Flexor accessorius (The “ Caro quadrata ” of Sylvius). On the 
left side of my Orang there was not a vestige of this muscle, whilst on 
the right side Rudolf found a very thin muscle possessing two heads of 
origin from the os calcis, and inserted into the tendon of the flexor digi- 
torum tibialis. 
Bischoff^ states that he has never found the accessorius in any 
anthropoid ape. But Langer,^ Fick,® and Chapman^ have found it 
weakly developed in the Orang. Hepburn^ and Gratiolet and Alix® 
have found it in the Chimpanzee. Huxley^*’ found it well developed in 
the Gorilla; it was also found in that animal by Hepburn and Macalister. 
As far as I am aware it has not been reported in the Gibbon. It would 
appear to be absent in most cases in the Gorilla. On the other hand 
according to Bischoff and Huxley it is present in the lower apes. 
It has been suggested that the accessorius is present in young anthro- 
__ poids but disappears in the old ; this view is however not tenable as it 
has been described as absent in many young animals. Fick points out 
that in the foot of the Orang an accessorius muscle is not necessary, as 
the foot is always strongly supinated and the flexor tendons pull in a 
straight direction and not, as in the foot of man, obliquely. The 
1 Loc. cit., Vol. II, p. 40. 
2 Loc. cit., p. 186. 
3 Loc. cit. I, 231, and 2, p. 30. 
4 Loc. cit. 2, p. 31. 
5 Loc. cit., p. 140. 
6 Loc. cit. 2, p. 304. 
7 Loc. cit., p. 164. 
8 Loc. cit., p. 341. 
9 Loc. cit., p. 203. 
10 Loc. cit., Vol. I, p. 538. 
