_ 128 — 



type of a Balaenoptera-rib, which a.o. has two smooth surfaces, (anterior 

 and posterior), a firmly rounded exterior margin and an edge-like inner rim 

 passing towards the lowest quarter part into a more broadened bony rim. 

 More to the rear the upper knobby costal extremity becomes smaller, the 

 width of the rib narrower, and the cross-section of the rib more circular. 



In the last three ribs, to end with, we see a double curvature,faintly 

 marked in the 14th and most strongly pronounced in the 16th. In consequence 

 of this additional curve the distal rib end becomes gradually bent more 

 backwards. 



The sternum (fig. 37 & 38) is a flat, rather small bone, somewhat 

 asymmetrical, broad 62 c.M., high 51 c.M.. It possesses a descending odontoid 

 process and two wings. Its shape presents an unmistakable similarity to that 

 described of some specimens of Balaenoptera physalus L.. Generally speaking, 

 however, the sternum in Balaenoptera physalus does not adhere rigidly to one 

 type but varies rather considerably; vide numerous illustrations in True (6). 



The junction of the sternum with the first pair of ribs has been sche- 

 matically represented m fig. 38, which illustration is a free rendering of one 

 by Struthers, to be found in the often quoted work of True (6), p. 141, fig. 27. 



The scapula (fig. 39 & 40) is a broad, flat, very large, yet light bone 

 of a more or less fan-like shape. The upper margin is curved evenly and 

 very rough for the attachment of cartilage, which spreads forward and rearward 

 in large plates prolonging the plane of the bone and extending it considerably. 



The blade-bone itself measuring a length of 165 c.M. and a height of 

 107 c.M. presents an exterior surface, consisting, as brought out in the 

 illustration, of four parts, slightly concave here and there. The interior side 

 resting againt the ribs shows a number of more or less clearly rising bony 

 ridges. The big acromion, so characteristic of Balaenoptera musculus L., is also 

 enormously developed here, into a somewhat flat process curved anteriorly; it 

 displays a broadened, very rough front edge for the attachment of cartilage. 



The glenoid fossa of the scapula in which the head of the humerus arti- 

 culates, is rather shallow, covered with a tegument of cartilage and thus 

 very smooth; the rim of the articular fossa is scabrous for the attachment of 

 cartilage, by which the articular surface is considerably increased. The neck 

 of the shoulderblade at the top of this, shows as may be seen in the illustration, 



