ON THE GREENLAND RIGHT-WHALE. 117 



ribs (the third and the tenth). As we have stated just now, the cartilaginous cord, enclosed in its 

 thick, perichondria! sheath, and evidently analogous to the neck of the rib in its state of complete 

 ossification, has always appeared to us to be attached to the intervertebral substance ; but it is 

 very difficult in parts so soft, and having such solid exterior sheaths as this perichondrium, to 

 point out the places of attachment with precision; and we have therefore been unwilling to 

 give up entirely the supposition mentioned above, that the necks of the ribs may properly be said 

 to be attached to the preceding vertebra.. 



By considering the fact that in many cases these cartilaginous cords are not continued 

 throughout the thick clothing of ligamentous membranes, especially not in the third pair of ribs 

 and the short-necked ribs generally speaking, we shall surely obtain a correct notion of the 

 strange way in which the two foremost pairs of ribs are attached in the Greenland whale, as well 

 as in all other whalebone-whales. We know that both these pairs of ribs have their proximal ends 

 attached to the transverse processes of the cervical vertebrae by means of extremely strong ligaments, 

 the first pair even especially to the second cervical vertebra. But besides they are, indeed, also 

 attached to the extremities of the two corresponding dorsal vertebrae, especially by means of 

 ligaments arising from immediately behind their obtuse extremities; and it has already been 

 intimated that it is this which evidently corresponds with the attachment common to all the ribs, 

 however unimportant it may seem to be when compared with that with the vertebrae placed in 

 front. For all those ligaments by means of which these two foremost pairs of ribs are attached 

 to the transverse processes of the cervical vertebrae, we must consider as corresponding to 

 those thick cords of the succeeding ribs, which are most commonly, though by no means always, 

 at least not in their entire length, developed into osseous necks of ribs. Nay, we should not 

 wonder if the inferior transverse processes of the cervical vertebrae themselves might be con- 

 sidered as homologous with the innermost part of those osseous shafts, even though they are 

 separated from the ribs, and form inseparable parts of the vertebrae. 



The ribs of the Greenland whale are, as usual, in the greater part of their length curved in 

 such a way as to have an external convex and an internal concave surface, the former of which is at 

 the same time turned somewhat backwards, the latter somewhat forwards ; and the external surface 

 is not only convex longitudinally, but also transversely. In the uppermost fourth, however, the 

 appearance of most of the ribs is very considerably altered, and in a manner which is very diffi- 

 cult to describe. The external convex surface is here twisted round, so that the posterior edge 

 the bone becomes very prominent on the inner surface (especially so in all the middle ribs from 

 the third to the tenth) ; but in the same upper fourth each of these bones is distorted so as to 

 have the inner concave surface turned backwards, by which means also the articular face placed 

 on this very surface receives a directly inward and backward direction towards the extremity of 

 the corresponding transverse process. This distortion is most visible in the third pair of ribs. 

 That inverted part of the posterior edge is, at its inferior termination, very prominent in most of 

 the ribs in the shape of an angulus costæ. 



In the inferior ends of the ribs it is not so easy to point out distinguishing marks for each 

 of them, as it is in the superior ends. We shall scarcely, however; find it difficult here to 

 distingush at least the four foremost by their considerable breadth, and the four or five hindmost 

 by their slender form, from the four or five middle ones. 



We have at length succeeded, by the assistance of our Greenland whale foetus preserved in 

 spirits of wine, in clearing up a not unimportant question as to the structure of the thoracic cavity 



