1 68 A BOOK OF' WHALES 



* 



threaten danger, the Megaptera will endeavour to 

 rescue its friends from the danger which environs 

 them, and will accompany them until they arrive close 

 to shore and have escaped the Sperm whales, of 

 whose real ferocity Lacepede is so fully convinced. 



The genus RHACHIANECTES may be thus defined: 

 Dorsal fin none ; throat plaits reduced to two. 

 Scapula high. 



This genus was described some years since by 

 Cope. I am able to write the following brief notice 

 of the principal characters of the skeleton, after 

 examining a complete skeleton in the British 

 Museum. * 



The skull of the whale is, on the whole, Rorqual- 

 like. It is, however, narrower anteriorly than in 

 Rorquals ; and this is accounted for on a lateral 

 view by the fact that the pre-maxillaries are, as it 

 were, pinched up in the middle line by the maxillaries 

 and are quite visible from the side. In this feature 

 the skull of Rhachianectes resembles that of a Right 

 whale. In Balcenoptera those bones are hardly 

 visible on a lateral view of the skull. In other 

 respects the skull of Rhachianectes differs but slightly 

 from that of Balcenoptera. 



In the vertebral column the atlas was missing; the 

 remaining vertebrae are quite independent of each 

 other as in the Rorquals ; and they have the wide 



* See for notes on Osteology v. BENEDEN, Bull Ac. Belg., xliii (1877), 

 p. 92, and MALM, Bik. Svcnsk Akad., viii. (1883). 



