1898-99. | THE ANATOMY OF THE ORANG OUTANG. 39 
n 
is found in the ape. Langer,' Fick,’ Bischoff,* Huxley,* Chapman, and 
others have failed to find a trace of the flexor longus pollicis in the 
Orang. Duvernoy, in the Gorilla, describes the flexor as going to the 
index finger and from this a slender tendon is detached for the thumb, 
which takes the place of the flexor longus pollicis.’ Brooks’ in dis- 
secting an Orang found that the two heads of the flexor brevis pollicis 
were separated at their insertion by a slender tendon which, he con- 
sidered, represented the flexor longus pollicis; this tendon was inserted 
into the ungual phalanx, and it could be followed up the forearm, but 
about two inches above the wrist it expanded into areolar tissue. 
Among the anthropoids one finds a rudimentary tendon going to the 
thumb, this is derived from the flexor tendon which is distributed to the 
index finger. Thus in the Chimpanzee, Huxley and Macalister both 
describe a very slender tendon to the thumb from the flexor longus 
digitorum tendon for the index finger.’ A similar condition is found 
by Bischoff and others in the Gorilla and the Gibbon. Among the 
lower apes of the old world (Cynopithecini) Huxley found a rudi- 
mentary slender tendon to the pollex derived from the flexor tendon to 
the index, a condition similar to that in the anthropoids named. 
Among the Lemurs (Stenops tardigradus) the same authority states, 
that a true and distinct flexor longus pollicis of separate origin and 
insertion exists. Similar observations have been made by Bischoff 
regarding the lower apes and the rudimentary condition in them of the 
flexor longus pollicis. The anthropoid apes and the lower apes there- 
fore resemble one another in respect to this muscle, whilst they all differ 
from man where the flexor longus pollicis is developed as a strong 
muscle completely separated from the flexor profundus digitorum, a 
condition never yet found in the ape. It is not common to find much 
variation in the development of the flexor longus pollicis in man, but 
such does occur occasionally. Turner® placed on record several cases in 
which the flexor longus pollicis contributed a tendon of communication 
1 Loe. cit,, p. 180, 
2) oe. cit. ps 23% 
3 Loc. cit.1,0p. 214. 
4 Loc. cit., Vol. I, p. 506. 
5 Loc. cit., p. 162 
6 Loc. cit., p. 106. 
7 H. St. John Brooks, ‘‘On the Short Muscles ot the Pollex and the Hallux of the Anthropoid Apes 
with Special Reference to the Opponens Hallucis.”” Journ. of Anat. and Phys., Vol. XXII, 1887-8, p. 82. 
8 Loc. cit., Vol. II, p. 145. 
9 W. Turner, ‘On Variability in Human Structure, with illustrations from the Flexor Muscles of the 
Fingers and Toes.’ Transactions of the Royal Society of Edinburgh, Vol. XXIV, 1867, p. 170. 
