308 MR. J. BESWICK PERRIN ON THE 
the dermo-humeralis, which is so commonly present in birds. The latissimus dorsi. 
rhomboids, &c., presented no peculiarities. 
The coracoid and furculum are immovably fixed’. 
The subfurcular space, and the membrane which separates it from the cervico-axillary 
space, are very narrow and ellipsoidal in shape. 
The deltoid presents a similar arrangement to that met with in the Wood-pigeon, viz. 
a posterior detached portion inserted into the lower end of the outer border of the 
humerus and perforated by the musculo-spiral nerve, a middle portion, which mainly 
joins the tendon of origin of the extensor carpi radialis longior, and an anterior portion, 
which gives a contributory tendon to the extensor plice alaris. Virtually the posterior, 
corresponding to the spinal fibres of mammals, is the only part of the muscle belonging 
to the first arm-bone, unless the small muscle which is situated on a deeper plane, and 
inserted into the upper and dorsal extremity of the humerus, can be regarded as a portion 
of the deltoid rather than an infraspinatus muscle. 
Biceps flexor cubiti, though strictly speaking a monogastric muscle, has a tendency 
to divide proximally into two portions. It arises by a thin tendon, which becomes 
expanded as it crosses the shoulder-joint, thus playing a twofold purpose :—Ist, as a 
protective ligament to the joint; and, 2ndly, to allow the great pectoral muscle to glide 
freely over it. The tendon abruptly terminates opposite the lower border of the great 
pectoral in a strong fusiform muscular belly. In other respects the muscle presents the 
average avian distribution. 
The triceps is a digastric muscle. The humeral head, however, exhibits slight traces 
of a tendency to further section. It presents the average arrangement. 
Muscles of the Cubit. 
Pronator radii teres—Monogastric. Fusiform in shape. Attached proximally by 
a strong pointed tendon to the internal humeral condyle, distally to the middle of the 
shaft of the radius. 
Flexor carpi radialis—Large and fleshy. It springs from the inner condyle of the 
humerus beneath the preceding. It is inserted mainly into the lower third of the 
preaxial surface of the radius, and by a few fibres into the radial carpal bone. 
Flexor sublimis digitorum.—Springs from the inner humeral condyle by a strong flat 
tendon. It is fusiform in shape. Immediately above the carpus it terminates in a 
single tendon, which grooves the lower end of the ulna and afterwards runs along 
the superior border of the long (2nd) metacarpal. It is inserted into the middle of 
the antepenult phalanx. 
Palmaris longus.—Is simply represented by a strong flat and ribbon-like band of 
fascia, extending between the inner condyle of the humerus and the carpus. 
' Prof, Huxley says, “a rare peculiarity, which has been observed in Didus.” ‘Tn the ankylosis of the 
furcula with the manubrium, Opisthocomus stands alone.” Proc. Zool. Soc. May 14, 1868. 
