PROFESSOR OWEN ON THE AYE-AYE. 61 
The ‘long portion’ or ‘head’ (Pl. XXIII. fig. 2, 2) arises from the rough facet 
behind the glenoid cavity; the fleshy part is broad, thin, and short, ending in a broad 
tendon covering the lower half of the back part of the humeral muscles, and receiving 
the accessory head (ib. fig. 1, 2«) from the latissimus dorsi ; it is inserted into the 
olecranon. ‘The ‘external portion’ (ib. fig. 2, 2+) arises below the lesser tuberosity 
and contiguous part of the humeral shaft, and continues fleshy to near its insertion by 
a broad tendon into the outer border of the olecranon. The internal portion (7b. fig. 1, 22) 
arises from the inner and back part of the shaft of the humerus, beginning below the 
insertion of the teres major: it is thick and fleshy ; the fibres, converging to a very 
short but broad tendon, are inserted, with the preceding, into the olecranon, and are 
attached to the outer part of the capsule of the elbow-joint. The lower portion of this 
muscle is noted by Burmeister’ as an ‘ anconeus sewtus’ in the Tarsius, and appears to 
be almost as distinct a part in the Aye-aye (PI. XXIII. fig. 1, +). Its fibres come 
from above the entocondyloid ridge to near its lower end, and are inserted into the inner 
part of the olecranon. Vrolik* speaks of an auxiliary fascicle to the triceps from the 
back part of the humerus in Stenops. 
The supinator longus (Pl. XXIII. figs. 1 & 2, 2s) has its long fleshy origin extended from 
the middle of the humerus to near the end of the ectocondyloid ridge, where it is partly 
covered by the origin of the extensor carpi radialis longus: its fibres converge as they 
pass along the upper and fore part of the forearm, below the middle of which the 
tendon commences whereby it is inserted into the outer part of the carpal tuberosity 
of the radius. 
The extensor carpi radialis longus (P1. XXIII. fig. 2, ) arises from the lower part of 
the ectocondyloid ridge ; it is less broad than the supinator, from which it is divided by 
the radial nerve ; its tendon begins about the middle of the forearm, is crossed by the 
abductor longus pollicis (ib. 5), passes, with the tendon of the extensor carpi radialis brevis 
(ib. 26), through a synovial sheath in the dorso-carpal ligament, gives off a strong aponeu- 
rosis to the scaphoid and trapezium, and is finally inserted into the back part of the base 
of the metacarpal of the index finger. 
The extensor carpi radialis brevis (ib.2) arises from the outer and lower part of the 
ectocondyloid tubercle, in common with the extensor digitorum (ib. »7): its tendon begins 
lower down than that of the long carpal extensor, but has a similar course until it has 
passed through the dorso-carpal ligament (7), when it diverges to be inserted into the 
base of the metacarpal of the digitus medius. 
The extensor carpi ulnaris (Pl. XXIII. fig. 2, %) arises from the lowest part of 
the ectocondyloid protuberance: its tendon begins about the lower third of the ulna, 
near the end of which it passes through a pulley of the dorso-carpal ligament, and 
inclines outward to be inserted into the back and outer part of the base of the 
fifth metacarpal. 
' Op. cit. p. 32. ? Op. cit. p. 44. 
