ANATOMY OF THE LEMUROIDEA. 45 
From this it appears to us that the first and second heads represent the flexor longus 
pollicis, the other three heads constituting the flexor profundus digitorum, which thus 
exclusively supply the third, the fourth, and the fifth digits (woodcut, fig. 16). 
In Cheiromys we find but a single head to this muscle, but a very large one, extending 
from the internal condyle more than three-fourths down the forearm. Its tendon 
receives the tendinous communication (woodcut, fig. 17,**) from the sublimis, and 
immediately below this becomes adherent to the tendon of the flexor longus pollicis. 
It supplies exclusively the tendons of the fourth and fifth digits, and in great part that 
of the pollex, the portion from the sublimis merging in this pollicial portion. The 
thumb thus derives power from the profundus and sublimis as well as from its own 
powerful flexion. The tendinous fibres for the pollex derived from the profundus and 
sublimis cross over (are superficial to) the strong tendon of the flexor longus pollicis. 
FLEXOR LONGUS POLLICIS.—This is by far the largest muscle of the forearm, and is 
closely connected (at and near the interosseous membrane) with the flexor profundus, 
while about halfway down the forearm it receives a distinct slip from that muscle. 
It consists of two portions, which unite a little above the middle of the forearm. One 
part arises from the whole anterior surface of the radius (from the tubercle above to 
near the pronator quadratus below) and from the interosseous membrane. 
The other portion springs from the septum between it and the flexor sublimis and 
from the internal condyle. The slip from the flexor profundus joins the deep surface 
of the first and radial portion just below its junction with the second part. The muscle 
gives origin to a very strong tendon, which at the wrist becomes intimately united with 
that of the flexor profundus, and with it forms the deep flexor tendons, that for the 
pollex being given off from the radial side of the conjoined tendon a little below the 
junction. 
Only a fraction of this muscle is represented by Cuvier in his delineations of the 
myology of the Lemuroids, pl. 68. fig. 2, A. 
Lemur varius and L. nigrifrons present no difference from L. catta; and the Galagos 
are substantially the same. ‘That of Galago crassicaudatus is figured in Pl. IV. fig. 14, 
Filp', and F.l.p*. In G. peli no distinct flexor longus pollicis is described by 
KKingma. 
In Loris gracilis there is a greater resemblance to the condition found in Nycticebus, 
to be described presently; but it sends no tendon to the third and fourth digits. It 
contributes to form the deep flexor tendon of the pollex and those of the index and 
third digits, but supplies no digit exclusively, as in the latter genus. 
Contrary to what obtains in Zemur and Galago, Nycticebus tardigradus has the flexor 
longus pollicis remarkably distinct from the flexor profundus, which, moreover, it con- 
siderably exceeds in size. It supplies exclusively the deep flexor tendon of the third 
digit, and contributes to form that of the hallux and fourth digit and the main part of 
that of the index. 
