62 PROFESSOR OWEN ON THE AYE-AYE. 
The extensor digitorum communis (Pl. XXIII. fig. 2,27), arising, in common with the 
extensor carpi radialis, from the ectocondyloid tubercle, accompanies that muscle in close 
attachment therewith down half the forearm, then separates therefrom to allow the 
abductor longus pollicis (ib. 25) to glide between them, and at about the same part of the 
forearm itself divides into two fasciculi terminating in the extensortendons. These pass 
beneath the dorso-carpal ligament, beyond which they are connected together by strong 
fascie, forming, apparently, a broad band upon the metacarpus where the separate tendons 
diverge to the second, third, fourth, and fifth digits. They expand as they pass over the 
proximal joints, where they are connected with the divisions of the shorter extensor 
tendons. A deep-seated extensor, forming almost a separate muscle, sends subsidiary 
tendons (27 «) to the fourth and fifth digits, expanding upon the capsules of the proximo- 
digital joints. In this respect Chiromys resembles Tarsius', and differs from Stenops, in 
which, according to Vrolik*®, the deep extensor of the fourth and fifth fingers is 
wanting. 
The abductor longus pollicis (Pl. XXIII. fig. 2, 2) arises from the lower part of the 
ectocondyloid tuberosity, descends on the radial side of the extensor longus pollicis as far 
as the middle of the antibrachium, then diverges obliquely radiad, decreasing in breadth 
as it passes over the tendons of the two radio-carpal extensors, passes with them through 
the dorso-carpal ligament, and goes to be inserted into the radial side of the metacarpal 
of the pollex. 
The extensor longus pollicis (Pl. XXIII. fig. 2, s7) arises from the upper third of the 
ulna, passes down the back part of the interosseous space, becomes tendinous at the 
lower third of the forearm, bends radiad beneath the index and medius tendons of the 
common extensor, and, after passing through the dorso-carpal ligament, proceeds to 
its insertion into the back part of the proximal phalanx of the thumb. 
Beneath the foregoing, arising from the middle of the ulna and interosseous ligament, 
is a small muscle, answering to the ‘ indicator,’ but dividing into two slender tendons, 
which, after connexion with those of the superficial extensors, go respectively to the index 
and medius digits, dividing upon the proximal phalanx, and uniting to be inserted into 
the base of the distal phalanx. 
Some of the smaller muscles of the digits are indicated in the description of the Plates. 
The forearm of the Aye-aye appears to be incapable of being naturally brought into a 
straight line with the humerus, but freely bends within the limits of the obtuse angle to 
which it can, with moderate force, be stretched. 
The pronator teres (Pls. XXII. & XXIII. fig. 1, »2) arises, in close connexion with the 
palmaris longus, from the lower and fore part of the entocondyloid ridge, and is inserted 
by a broad flat tendon into the radius at and above its middle part. The carneous 
fibres continue on the outer part of the muscle to near its insertion. 
The flexor carpi radialis (ib.»), with a similar but deeper origin, continues fleshy 
* Burmeister, op. cit. * Op. cit, p. 45. 
