COMMON RORQUAL. 397 



GET A CEA . BA LJBNOPTERIDJE. 



(MYSTACOCETI.) 



GENUS BAL^ENOPTERA (Lacepede, 1804). 



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

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

 Cervical vertebrae usually free, scapular with a distinct acromion and coracoid 

 process. 



COMMON RORQUAL OR RAZOR-BACK. 



Bal&noptera 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. Vertebrae 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. 



4 



Balcena musculus, LINNJEUS, Syst. Nat. (1766), I., 106. 



,, antiquorum, FISCHER, Syst. (1828), 525. 

 Physalus J. E. GRAF, P.Z.S. (1847), 90. 



Keporkanak of Greenlanders. Porhval of Swedes. Razor-back and Fin- 

 back of English whalers. 



THE second genus of Balanopterida 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 nippers, of which the middle 

 digits have not more than six joints. 



