— 126 — 



length of the 15th rib, whereas the very last rib is again slightly longer (227 

 C.M.): a fact by which the Buitenzorg skeleton deviates surprisingly from 

 the Balacnoptera with whose descriptions I am familiar, in which if present 

 at all, the 16th pair of ribs is merely rudimentary. 



As compared with the ribs of Balaenoptera physalus L. the illustrations 

 given present a good many deviations. 



The first pair of ribs is faintly arched, consisting of a flattened, elongated 

 and rounded upper end which is rough for the attachment of ligamentous 

 bands and hardly makes the impression of a separate capitulum and which 

 is articulated laterally between the bodies of the last cervical and the first 

 dorsal vertebra: this first rib, unlike all other costae, does not rest against a 

 lateral process. The lateral process of the first vertebra thoracis, it is to be 

 noted, is still very flat and is very abruptly curved downward, as a result 

 of which it approaches the exterior of the capitulum of the rib with a rough 

 edge, being connected with it by ligamentous tissue. The lower or ventral end 

 of the first rib is not much broader than the dorsal end, which according to 

 illustration is the case with most other varieties of Balaenoptera. Neither is 

 the first rib, as usually stated, the broadest; the greatest breadth is met with 

 in the 3rd, 4th and 5th costae, amounting to as much as 19 c.M.. The lower 

 end of the first rib displays a rough surface for the attachment of cartilage 

 and connective tissue by which it is joined on to the sternum. A little way 

 upwards a rough part of the lower end of the first ribs shows a second place 

 of attachment. The front surface of the rib is flat, the middle showing a 

 broader and thicker part furnished with several grooves and rough ridges 

 which continue on the exterior part of the equally flat posterior surface. This 

 points to the attachment of a very powerful muscle, namely the exterior head 

 of the oblique neck-muscle, sterno-mastoideus. The first pair of ribs consoli- 

 dated with the breastbone and with the vertebral column forms with these a 

 firm bone ring, which in the nature of the case can resist the action of 

 muscles better than the asternal ribs following immediately behind. The sterno- 

 mastoideus being the most powerful muscle joining the head and trunk, it 

 is intelligible that for the attachment of its tendons such a large and exceptio- 

 nally scabrous surface is required on this more firmly fixed first rib. 



The second rib has, like the first, a rough elliptical capitulum, articulated 

 laterally to the first two vertebral centra and approaching from below the 

 transverse process of the second vertebra, from which it still remains a 



