136 



B AL.5:N0 PTERI D^ . 



It has been suggested to me by a comparative anatomist of con- 

 siderable experience that perhaps the lateral processes of the cervical 

 vertebrae of this whale miglit be lengthened in the adult, and the 

 end of the upper and lower processes united into a broad expanded 

 plate as in the genus PJii/salus. 



In the skeleton of the small foetus of Balcenoptera, only 9 inches 

 long, figured by Eschricht in the ' Royal Danish Transactions ' for 

 1846, t. 14. f. 2, the lateral processes of the second vertebra are very 

 nearly of the same shape as in the adult, forming a broad expansion, 

 with a perforation at its base. The cer%'ical and other vertebra) of 

 this foetus seemed to agree, in all details of form, with the same 

 bones in the adult. 



I do not deny that the lateral process of the first corneal vertebra 

 may not be continued in cartilage, and be of the same form as that 

 of the genus Pluisalus ; but at any rate we have no proof, if this be 

 the case, that the cartilage at the end ever becomes ossified in this 

 genus any more than in the genus Megaptera, both genera agreeing 

 in the eqiiality of the thickness and strength and shortness of the 

 lateral processes. 



Fig. 24. 



Second cervical vertebra of Benedenia Knoxii. 

 Extreme width 19 inches; height 10 inches. 



The genera Megaptera and Benedenia have separate, short upper 

 and lower lateral processes, which are rather dilated and truncated 

 at the end, having an interriipted circular perforation between their 

 inner bases. It has been suggested that, in the latter genus at 

 least, the separated processes may be only the imperfectly developed 

 state of the broad lateral process of the genus Pligsalus, the end 

 that is wanting in the skeleton probably existing in the living animal 

 in the state of cartilage. Bnt if this should be the case (which I 

 much doubt), the form of the margin of the perforation and the per- 

 foration itself must undergo great change during the ossification of 



