SCHULTE, SEI WHALE. 419 



The long head of the triceps arises from the caudal extremity of the glenoid cavity, the 

 glenoid ligament and capsule of the shoulder joint. The belly is broad and flat and rrarkcdly 

 convex along its dorsal margin. It is inserted by a short tendon into the extremity of the long 

 olecranon process. The external head, triangular in shape, arises from the postaxial border 

 of the humerus in its distal half. Its fasciculi are inserted into the whole length of the cephalic 

 border of the olecranon save for the area at the tip occupied by the long head. The third head 

 I failed to find. Its presence is recorded in B. rostrata by Carte and McAlister. Perrin does 

 not describe the triceps but his illustrations show only a long and an external head. 



Trachelo-costo-scapular muscles. The serratus anticus is best developed at the caudal 

 angle of the scapula. Here strong slips from the 4th, 5th and 6th ribs converge to an insertion 

 at the angle itself and the adjacent surface. Except in this region I failed to find fasciculi of 

 this muscle. Carte and MacAlister found it arising from the eight caudal ribs with a slip from 

 the second. Its nerve supply is from the long thoracic nerve. 



The levator anguli scapulae is a short thick muscle arising from the costal process of the 

 second cervical vertebra. It passes between the scalenus and the trachelo-mastoid turning 

 dorsad to be inserted into the ventral aspect of the cephalic angle of the scapula. It is supplied 

 by ventral branches of adjacent cervical nerves. 



Rhomboideus. The rhomboideus is not cleft into major and minor, but .forms a narrow con- 

 tinuous sheet along the whole length of the suprascapula. Its origin does not extend to the 

 spines of the vertebrae, but takes place by muscular fasciculi from the dorsal aponeurosis over 

 the longissimus dorsi. 



Scapula-humeral muscles. The deltoid is the largest of this group. It arises from the 

 rostral two fifths of the dorsum scapulae as far caudad as the infraspinatus, which it overlaps 

 by its caudal margin, further from the ectal surface and ventral border of the acromion process, 

 and from the fibrous' tissue, which bridges the angle between this process and the rostral border 

 of the scapula, serving as an intermuscular septum between the deltoid and the supraspinatus. 

 The muscle is coarsely fasciculated. Its bundles converging towards the head of the humerus 

 are inserted upon a tendon, which appears first on the surface and caudal border of the muscle. 

 Into this the fasciculi of acromial origin insert along its preaxial border as it approaches the 

 humerus, so that here the muscle is fleshy to its insertion. Some of these fasciculi reach the 

 radial tuberosity of the humerus inserting between the infraspinatus dorsad and the masto- 

 humeral and supraspinatus ventrad. The tendon after crossing that of the infraspinatus, 

 which separates it from the shoulder-joint, is inserted into dorsal surface of the humerus from 

 the neck distad and into the whole preaxial border of that bone, blending distad with the capsule 

 of the elbow and extending upon the radius, and above expanding into the deep fascia, of the 

 flexor surface of the arm. 



Perrin describes a strengthening band of the capsule of the shoulder passing from the glenoid 

 margin and the base of the coracoid to the humerus. This is here represented by a small sub- 

 deltoid muscle. It arises, as Perrin's ligament from the base of the coracoid and the margin 

 of the glenoid cavity, but is much narrower. Its tendon rests upon the capsule of the shoulder 

 joint which it crosses on its rostro-lateral aspect to be inserted into the tuberosity of the humorus 

 under cover of the deltoid, between the infraspinatus and the fleshy insertion of the deltoid 

 which separate it from the cephalo-humeralis and supraspinatus. Both of these muscles are 

 supplied by the circumflex nerve. 



