COMMON RORQUAL. 



397 



CETACEA. 

 (MYSTACOOETI.) 



BAL^NOPTERID^. 



Genus Bal.enoptera (Lacepede, 1804). 



Generic Character. — Skiu of throat and belly plaited ; a well-defined com- 

 Ijressed dorsal fin ; flippers short, their edges even ; head and body slender. 

 Cei-rical vertebras usually free, scapular with a distinct acromion and coracoid 

 process. 



COMMON RORQUAL or RAZOR-BACK. 



Balmnoptera musculus (Linnaeus). 



Specific Character. — Black above, shaded to a brilliant white below ; flip- 

 pers black ; baleen slate-colour, streaked with paler shades. Upper jaw 

 pointed; dorsal-fin high, distinct. Vertebrie 61 or 62; ribs 15 pairs, the 

 first usually single-headed ; sternum trilobate, not longer than broad. Length 

 of adult 60 to 70 feet, or a little more. 



Balana mitsculus, Linn-eus, Syst. Nat. (1766), I., 106. 



,, antiquorum, Fisobek, Syst. (1328), 525. 

 Phijsalus ,, J. E. GBAr, P.Z.S. (1847), 90. 



Keporhanalc of Greenlanders. Forhval of Swedes. Razor-bach and Ein- 

 back of English whalers. 



The second genus of Balcenopteridce contains the true 

 Rorquals or Fin-whales, separated from the Hump-back 

 by their more slender form, smaller head, and more dis- 

 tinct and compressed dorsal-fin, as well as by the com- 

 parative shortness of their flippers, of which the middle 

 digits have not more than six joints. 



