154 A BOOK OF WHALES 



that feeds upon Crustacea, mainly, it appears, upon 

 a species of Euphansia, known to the Scandinavian 

 whalers as " Krill." These Crustacea have been 

 discovered in vast numbers in the stomach of 

 captured whales. Balccnoptera sibbaldii is a species 

 that lives mainly in pairs, and reproduction seems to 

 take place every three years, more slowly than in the 

 case of the smaller species of Balccnoptera. 



Balcenoptera boreal is, Lesson* ( = J3> rostrata, 

 Rudolphi ; B. laticeps, Gray) ; is in length 40-52 

 feet. Height to length as i : 5^-. Colour bluish 

 black above, below white ; upper surface with oblong 

 light spots. Dorsal fin high, a little in advance of 

 last third of body. Vent exactly below hinder edge 

 of dorsal fin. Pectoral fins small, -^ of total length 

 of body. Baleen black with white bristles; number of 

 plates 330; greatest length 650 mm. (See Fig. 22.) 



Of this species, known as Rudolphi's Rorqual, and 

 by the Norwegians as Sejhval, a very complete 

 account of external characters and habits is given by 

 Professor Collett. 



As will be seen from the dimensions given in the 

 above definition, this is a moderately-sized Rorqual. 

 It seems clear, therefore, that even allowing for the 

 inevitable exaggeration that seems to have accom- 

 panied most descriptions of whales, at any rate in the 

 past, it cannot be identical with the " Ostend whale" 



* Hist. Nat. Cetac., 1828, p. 342. "On a Specimen of Rudolphi's 

 Rorqual (Balcenoptera borealis) lately taken on the Essex Coast," Proc. 

 Zool. Soc., 1883, p. 513. 



