Fig. 1. Left pectoral region of Majaqueus a@quinoctialis, to show the double 
pectoralis major (sew primus) muscle. Its superficial layer (p.1a) has been for the 
most part removed, its cut origin from the sternal crest and furcula (/.) being reflected : 
wp. 1a’, its insertion into the humerus, also cut and reflected. jp. 1b. The deep layer. p. 2. 
Fascia covering the pectoralis secundus muscle. t.p. Belly of tensor patagw muscles. 
t.p.l. Their tendon, joined by b.s. (biceps-slip) formed by the humeral head of the 
biceps humert muscle. b. Main belly of biceps muscle, formed by the coracoidal 
head. S. Body of sternum, bare of muscular fibres. 
Fig. 2. Dissection of left pectoral region of Diomedea brachyura to show the two 
layers of the pectoralis primus muscle (p. 1a, p. 1b), which have been cut and removed 
in large part, and the compound pectoralis secundus. jp. 2. Its sternal origin ; p. 2’, its 
coracoid origin; p. 2”, its furcular origin; p. 2’”, origin from coraco-furcular membrane 
(cfm). p. 8. Pectoralis tertius. C. Coracoid bone. F. Furcula, at symphysis. S. 
Sternum. (The line above it shows the limit of origin of the deep layer of the 
pectoralis primus.) 
Fig. 3. Dissection of right wing of Oceanites oceanicus, to show the peculiar 
expansor secundariorum muscle. e.s. Tendinous portion arising from the last remiges 
(S.). es’. The other moiety, arising from the last scapular feathers (Sc). p. 1. 
Pectoralis primus muscle, to which the expansor secundariorwm is attached. H. 
Humerus. Pat. Patagial membrane. v.n. Vessels and nerves to wing. 
Fig. 4. Left shoulder joint, inner side, of Ossifraga gigantea, to show the peculiar 
biceps muscle. c. Its coracoid head, continuous below with the belly of the muscle 
(b). h. Its humeral head, which forms a biceps-slip, joining the tendon of the 
tensor patagu (t.p). p.1. Insertions (cut) of the two layers of the pectoralis 
primus muscle. e. Extensor, t. Teres. c.b.l. Coraco-brachialis longus. .b.b. Coraco- 
brachialis brevis. 
Fig. 5. Same parts in Thalassiarche culminata. ¢.,h. Coracoid and humeral heads 
of biceps, here uniting below into the common tendon of that muscle (b.) bs. 
Biceps slip, largely tendinous and joining the tensor patagii near the elbow, derived 
from the coracoid head of the biceps. 
