358 ME. J. BESWICK PEERIN 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 plicae 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 cuMti, 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: — 1st, 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. — Moiiogastric. 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 digitormn. — 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 Didtis." " In the ankylosis of the 

 furcula-with the manubrium, Opistlioconius stands alone." Proo. Zool. Soc. May 14, 1868. 



