PROFESSOR OWEN ON THE AYE-AYE. 61 



The ' long portion ' or ' head ' (PI. XXIII. fig. 2, 22 a) arises from the rough facet 

 behind the glenoid cavity ; the ileshy 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, 22^) from the latissimus dorsi ; it is inserted into the 

 olecranon. The ' external portion' {ib. fig. 2, 22s) 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 {ib. fig. 1,22c) 

 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 sextus' in the Tardus, and appears to 

 be almost as distinct a part in the Aye-aye (PI. XXIII. fig. 1, 22 e). 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 (PI. XXIII. figs. 1 & 2, 23) 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 (PI. XXIII. fig. 2, 24) 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. 25), passes, with the tendon of the extensor carpi radialis brevis 

 {ib. 26), through a synovial sheath in the dorso-carpal ligament, gives ofl' 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 (i&.se) arises from the outer and lower part of the 

 ectocondyloid tubercle, in common with the extensor digitorum {ib. 27) : 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 {x), when it diverges to be inserted into the 

 base of the metacarpal of the digitus medius. 



The extensor carpi ulnaris (PI. XXIII. fig. 2, 28) 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. 



