490 SCHULTE, SEI WHALE. 



abruptly planed off when it joins the flexor surface of the shaft, so that here it rises very slightly 

 above the level of this surface, from which it is separated by an arched margin. The articular 

 surface of the humerus exceeds that of the glenoid fossa considerably in the transverse diameter, 

 to only a slight degree in the sagittal, so that it may be inferred that the movements of ab- and 

 adduction are more free than those of flexion or extension. The capsule of the scapulo-humeral 

 articulation is attached close to the margins of the articular surface, the neck of the humerus 

 being extremely short and marked only by a groove between the head and radial tuberosity 

 in which the capsule is attached. This tuberosity juts out from the preaxial border, its flexor 

 and extensor surfaces falling into the level of the corresponding surfaces of the shaft. Proxi- 

 mally it presents a quadrangular surface which like the rest of the tuberosity is rough for muscu- 

 lar attachments. Further mesad, close to the articular surface, on the flexor surface and not at 

 the postaxial border is a second rough and slightly projecting area into which the subscapularis 

 muscle is inserted. It is separated from the radial tuberosity by a groove which lodges the 

 tendon of the masto-humeralis. The shaft is oval in section proximad becoming more flattened 

 towards the elbow. The margins are concave, especially the postaxial. The extensor surface 

 is convex, the flexor rather flat. Distad there are two articular surfaces separated by a low 

 ridge for the radius and ulna, the latter being considerably the larger. Only the middle third 

 of the shaft is ossified and here the process seems less in degree than in the shafts of the radius 

 and ulna. The length of the humerus is 14 mm., its greatest breadth from head to tuberosity 

 is 8 mm., that of the lower extremity is 7 mm., of the middle of the shaft 5.5 mm. The junction 

 of the humerus with the bones of the antibrachium is at an angle, the long axis of the humerus 

 deviating slightly in a dorsal direction from the long axis of the limb so that at this point both 

 the preaxial margin and flexor surface are slightly concave. 



Radius: The radius is the stouter of the bones of the antibrachium. It is slightly flattened 

 dorso-ventrally and the shaft presents a marked curvature, convex preaxially in the middle and 

 curved in the opposite sense at the two extremities. While occupying a smaller area than the ulna 

 upon the humerus, at the carpus its surface is the greater, articulating with the radiale and the 

 whole of the intermedium. The shaft is ossified, the extremities cartilaginous. The total length 

 is 18 mm., the proximal cartilage 3 mm., the distal 4.5 mm., the remaining 10.5 mm. being com- 

 prised in the ossified diaphysis. 



Ulna: The ulna is longer and more slender than the radius. Its proximal extremity is 

 prolonged upon the postaxial border of the humerus thus enlarging their articular surface. This 

 is on the whole concave comprising a smaller vertical and larger transverse portion, the two 

 meeting at a rounded angle. In this region the ulna is dorso-ventrally flattened. Here it is 

 joined by the very large olecranon cartilage which projects in a dorsicaudal direction. It is com- 

 pressed, broadens towards its free extremity which is convex giving the whole cartilage much 

 the shape of an ax-head. The shaft of the ulna is rounded and ossified. Its carpal extremity 

 again expands slightly and is flattened. It articulates with the ulnare and with the pisiform. 

 Its length is 22.5 mm., of which 10.5 mm. is occupied by the ossification of the diaphysis, 

 7 mm. by the proximal cartilage,. 5 mm. by the distal, thus corresponding closely with the 

 radius in the length of diaphysis and distal cartilage. 



Carpus: The carpus is wholly cartilaginous. In the first row there are four elements, 

 radiale and intermedium articulating with the radius, ulnare and pisiform articulating with 

 ulna, which is partially united with the ulnare. The carpalia are much reduced. Carpale 



