1898-99. | THE ANATOMY OF THE ORANG OUTANG. 537 
Gorilla, and the result of Hepburn’s investigations was that he found this 
muscle present in the Chimpanzee, Orang and Gibbon, but absent in the 
Gorilla. 
The palmaris longus, both in man and apes, would appear to be a 
rudimentary structure ; in many animals it is a well developed muscle 
and sends tendons to all the digits. From a comparative study of this 
muscle Bland Sutton’ and others have arrived at the conclusion that 
the palmar fascia of the human hand arises from the degeneration of the 
distal end of the palmaris longus muscle. According to Grapow’ the 
palmar fascia was first described as an expansion of the palmaris longus 
by Dupuytren in 1832. The view which Grapow holds concerning it is, 
that the main part of the palmar fascia is derived as a prolongation of 
the anterior annular ligament of the wrist, whilst the superficial, 
longitudinally coursing fibres are derived from the palmaris longus 
muscle. The muscle in man is very variable in its development, it is 
entirely absent in ten per cent. of all cases, and it presents great variety, 
not only in its points of insertion but also in the development of its 
fleshy and tendinous fibres. 
The Flexor carpi ulnaris arose in common with the flexors from the 
internal condyle, also from the inner side of the olecranon process of the 
ulna. The ulnar nerve passed into the forearm between the two heads. 
It was inserted into the pisiform bone. The muscle thus resembles that. 
found in man. 
The Flexor sublimis digitorum vel Perforatus arose from the common 
origin from the internal condyle and intermuscular septum, also from 
the coronoid process and the olecranon process and in common with the 
flexor carpi radialis from the oblique line of the radius. Passing beneath 
the annular ligament it there passed into the palm in four tendons, The 
tendon for the index finger and that for the little finger were derived 
mainly from fibres arising from the internal condyle. The tendon for 
the middle finger was derived mainly from fibres arising from the 
radius. The tendon for the ring finger was derived mainly from 
fibres having an origin from both the radius and the internal condyle. 
The fleshy mass from which the tendon for the index finger arose 
formed a very definite fasciculus which passed down on the deep 
aspect of the main part of the muscle along its ulnar border, and 
1 Loc. cit., p. 16. 
2 Max-Grapow, ‘Die Anatomie und Physiologische Bedeutung der Palmaraponeurose.”” Archiy fiir 
Anatomie und Entwickelungsgeschichte, 1887, p. 145. 
