COMMON RORQUAL. 



397 



GET ACE A. 

 (MYSTACOOETI.) 



BA L JEN OP TERJDjE. 



Genus Bal.t.noptera (Lacepede, 1801). 



Generic Character.— ?>km of throat and belly plaited ; a well-defined com- 

 pressed dorsal fin ; flippers sliort, tbeir edges even ; head and body slender. 

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

 process. 



COMMON RORQUAL or RAZOR-BACK. 

 Balanoptera 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. Yertebrte Gl 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. 



Balcena musculus, Linnaeus, Syst. Nat. (1766), L, 106. 

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



Physalus 



J. E. Gkav, P.Z.S. (1847), 90. 



Kcporkanak of Greenlanders. FOrhval of Swedes. Razor-bacJc and Fin- 

 back of English whalers. 



The second genus of Balcenopteridoi contains the true 

 Rorquals or Fin-wliales, 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 llipjK'rs, of which the middle 

 di<?its have not more than six joints. 



