i 9 o 5 .] 



ANATOMY OF PHAL/ENOPTILUS, RIDGWAY. 225 



cate being the m. propatagialis longus the lower and stronger ra. 

 propatagialis brevis. 



a. M. propatagialis longus {P. pat. 1., PI. V, Figs. 22, 24). 

 The tendon of this muscle runs along the anterior margin of the 

 patagium, with which membrane it is intimately connected. Thence 

 it continues as a very delicate tendon to the distal end of the radius. 

 It becomes flattened as it passes over the os radiale, and continues so 

 to its insertion. The flattened tendon passes to the ventral side of 

 the os magnum along its base, and is inserted on the posterior 

 proximal projection of the pollex digit. From this point a pyram- 

 idal-shaped tendon with its apex on the pollex-digit extends down 

 to the third metacarpal. 



b. M. propatagialis brevis (P. pat. b., PI. V, Figs. 22, 23) is 

 very complex in this bird. The tendon is larger than the longus 

 and flattened. It continues distally to the m. extensor metacarpi 

 ulnaris (radialis?) where it bifurcates, about 5 mm. from the distal 

 end of the humerus. The longer branch runs back with the m. 

 extensor metacarpi ulnaris (radialis?) to become inserted on the 

 humerus just distal to this muscle, and at the base of the tubercle 

 of the external condyle of the humerus. The shorter one continues 

 distally about 2 mm., then passes back obliquely to the m. extensor 

 digitorum communis and here it bifurcates, the proximal short 

 branch running back with the above muscle to insert itself on 

 the tubercle above the external condyle of the humerus and above 

 the origin of the m. ectepicondylo-radialis. The distal extending 

 branch becomes flattened at its insertion, which is at the base of the 

 styloid process of the radius on its ulnar side, near the m. extensor 

 pollicis longus and covered by it. From the second bifurcation 

 comes off a broad band which passes directly across to the ulna and 

 is inserted on that bone about 7 mm. or 8 mm. from its proximal 

 end. 



2. The metapatagium was torn away, so I can say nothing about 

 the ;;/. metapatagialis. 



3. M. biceps brachii, pars propatagialis {Pi., PI. VI, Figs. 20, 

 27 ; PI. II, Fig. 24). This large muscle lies on the anterior sur- 

 face of the forearm, and arises as two heads. The long head comes 

 from the anterior end of the coracoid as a strong, flat tendon. The 

 short head passes immediately into a stout muscle. The two pos- 

 teriorly unite to form a fusiform muscle which inserts at the elbow 



