SCHULTE, SEI WHALE. 421 



proportions of these structures in this foetus I doubt if they could be seen without recourse 

 to sections. In Perrin's specimen the origin extended proximad upon the humerus, and the 

 tendon of digit II gave off a slip to the metacarpus. This I could not find, nor does Struthers 

 mention its presence as a distinct element in B. musculus (= B. physalus), but finds all the 

 tendons united to the metacarpals in the same way as to the phalanges. 



The flexor carpi ulnaris arises from the distal margin of the olecranon and from the adjacent 

 shaft of the ulna to a slight extent. Its fasciculi converge to a long and slender tendon which 

 is inserted into the pisiform. It is identically the same as in B. musculus (Struthers) but differs 

 in its insertion from B. rostrata ( = B. acuto-rostrata) where Carte and MacAlister found it 

 inserting into the fourth metacarpal, Perrin into the ulna. 



The flexor digitorum radialis is a slender muscle arising from the postaxial portion of the 

 shaft of the radius as far distad as the middle of the bone, from the interosseous ligament, and 

 from the septum between it and the flexor ulnaris. Its tendon runs distad and towards the radial 

 digit where it joins the slip of the flexor ulnaris to that digit. 



The flexor digitorum ulnaris arises from the internal epicondyle of the humerus, the cap- 

 sule of the elbow joint, the shaft of the ulna in its proximal half, the interosseus membrane 

 and the intermuscular septum common to it and the flexor radialis. Its fasciculi converge upon 

 a slender tendon which upon reaching the carpus divides into four slips. These are continued 

 upon the flexor surface of the phalanges to the last. In this course the tendons are firmly bound 

 down to the phalanges and especially to the enlarged interphalangeal synchondroses, in the 

 last position by expansions of the tendon which are attached to the sides of the articular carti- 

 lages. The slip to digit IV continues the line of the main tendon, that to digit V is the strong- 

 est of the four. The slip to digit II is of approximately the same size, certainly not larger than 

 those to digits III and IV. I could find no trace of a palmaris longus described by Carte and 

 MacAlister, nor of the flexor sublimis found by Perrin, in B. rostrata (= B. acuto-rostrata). In 

 this as in other respects the intrinsic muscles of the flipper agree closely with the conditions 

 in B. musculus (= B. physalus) as recorded by Struthers. 



Abdominal muscles. The rectus abdominis is a broad and massive muscle, forming the 

 chief support of the abdominal wall and extending from the sternum to the pelvis as a con- 

 tinuous sheet uninterrupted by tendinous inscriptions. It arises from the ventral surface of 

 the sternum and the whole breadth of its caudal margin, and from the ventral extremities of 

 the first eight ribs and their cartilaginous prolongations. The costal slips diminish in size caudad. 

 Those from the second and following ribs arise from their caudal borders and add themselves to 

 the lateral border and deep surface of the muscle, which thus increases in breadth as well as 

 thickness in its thoracic portion. It attains its maximum width a little rostrad of the umbili- 

 cus and thence contracts again caudad. As it approaches the pelvis the rectus divides into a 

 medial and a lateral portion separated by a large neurovascular foramen, through which emerge 

 the nerves and blood vessels for the genitalia and proximal portion of the pedicle. The median 

 division of the muscle is narrow and inserts in large part upon the rostral border and ectal surface 

 of the ilium. The remainder expands into an aponeurosis interposed between the ischio-caudalis 

 and the hypaxial muscle, which inclining mesad joins with its antimere by its more rostral 

 fibres, forming an arch to give passage to the rectum and vagina, while its more caudal fibres 

 are attached to the proximal chevron bones in common with similar fibres from the opposite 

 side. The lateral division of the aponeurosis expands beneath the obliquus internus and pan- 



