420 SCHULTE, SEI WHALE. 



The supraspinatus, covered by the deltoid, is a larger muscle and of more extensive origin 

 than in the porpoise (Rapp, Stannius) and yet far from attaining half the size of the deltoid 

 as found in B. rostrata ( = B. acuto-rostrata) by Carte and MacAlister, with whose description 

 it corresponds in general. It arises from the rostral border of the scapula as far ventrad as the 

 acromion, from the ventral surface of the acromion, and from a fibrous layer, which closes the 

 angle between scapula and acromion and gives origin by its ectal surface to the deltoid. The 

 fasciculi converge to a tendon, which passing upon the rostral aspect of the shoulder-joint is 

 inserted into the radial tuberosity of the humerus under cover of the tendon of the masto- 

 humeral. It is supplied by the suprascapular nerve. 



The infraspinatus arises from the vertebral margin of the scapula in its third and fourth 

 fifths and from the corresponding portion of its dorsum as far as the neck. The muscle is tri- 

 angular, abutting upon the origin of the teres by its caudal margin, overlapped by the deltoid 

 along its rostral border. After crossing the long head of the triceps it passes into a flattened 

 tendon, applied to the dorsum of the shoulder-joint, to which it is adherent, then expanding 

 somewhat it is inserted into the radial tuberosity of the humerus on its extensor aspect. At 

 its insertion it is embraced by the expansion of the deltoid. It is innervated by the supra- 

 scapular nerve. 



The teres arises from two thirds of the caudal border of the scapula adjacent to the neck 

 and from a firm intermuscular septum common to it and the subscapularis. Its tendon crosses 

 that of the latissimus dorsi very obliquely being intimately united with its dorsal surface, and is 

 then inserted into the shaft of the humerus distal to the subscapularis. Its nerve is derived 

 from the long thoracic in its course through the axilla. 



The subscapularis occupies the whole venter of the scapula. It is partially divided at its 

 origin into eight fleshy slips. Its fasciculi converge to a narrow insertion upon the postaxial 

 surface of the humerus immediately below the head, and by an aponeurotic expansion into the 

 fascia of the flexor surface of the arm. It is supplied by small branches of the long thoracic. 

 Its tendon is firmly united with the capsule of the shoulder, not perforating it as Carte and 

 MacAlister describe, but can be separated leaving the joint intact, in this corresponding with 

 the observations of Perrin. 



Intrinsic muscles of the flipper. The extensor communis digitorum arises from the capsule 

 of the elbow-joint and from the adjacent surfaces of the ulna and radius together with their 

 interosseus membrane. The ulnar origin is small being confined to 3 or 4 mm. of the proxi- 

 mal portion of the bone. On the radius the origin includes the proximal three fifths of the 

 shaft. The tendon appears first at the ulnar border of the belly and before the carpus is reached 

 has received all the fasciculi of the muscle. On the carpus the tendon expands and divides into 

 four slips. The middle two follow the axial lines of the two middle digits. The postaxial slip 

 follows the preaxial border of the ulnar digit; the preaxial slip the postaxial border of the radial 

 digit. In their whole length these tendons are united by fibrous tissue to the perichondrium 

 of the phalanges and the union is especially firm at the enlarged interphalangeal joints. I 

 could not make out the definite lateral slips in the region of the joints, which Struthers ] mentions 

 in his beautiful description and illustration of this muscle in B. musculus ( = B. phy solus), and 

 which Carte and MacAlister describe in B. rostrata ( = B. acuto-rostrata). From the diminutive 



1 Struthers, 1871. Op. cit., Jour. Anat, and Phys., Vol. VI, p. 107. 



