CHAP. XVIL] MAMMALIA. 207 



Order V.CETACEA. 

 FAMILY 36. BAL^ENID^E. (6 Genera, 14 Species.) 



GENERAL DISTRIBUTION. Temperate and Cold Seas of both Northern and 

 Southern Hemispheres. 



This family comprises the whalebone or " right " whales, the 

 best known species being the Greenland whale (Balcena mys- 

 ticetus). Allied species are found in all parts of the southern 

 seas, as far north as the Cape of Good Hope ; while some of the 

 northern species are found off the coast of Spain, and even enter 

 the Mediterranean. As most of the species indicated are im- 

 perfectly known, and their classification by no means well 

 settled, no useful purpose will be served by enumerating the 

 genera or sub-genera. 



FAMILY 37. BALDEN OPTERID^E. (9 Genera, 22 Species.) 



GENERAL DISTRIBUTION. Cold and Temperate Seas of both Hemispheres. 



This family comprises the finner whales and rorquals, and are 

 characterised by possessing a dorsal fin and having the baleen 

 or whalebone less developed. They are abundant in all northern 

 seas, less so in the southern hemisphere, but they seem occa- 

 sionally to enter the tropical seas. The best known genera are 

 Megaptera (7 species) ; PJiysalus (4 species) ; and Balcenoptera 

 (2 species) ; all of which have species in the North Sea. 



FAMJLY 38. CATODONTID^. (4 Genera, or Sub-Genera, 

 6 Species.) 



GENERAIO DISTRIBUTION. All the Tropical Oceans, extending north and south 

 into Temperate waters. 



This family, comprising the cachalots or sperm whales, and 

 black-fish, are separated from the true whales by having teeth 

 in the lower jaw and no whalebone. They are pre-eminently a 

 tropical, as distinguished from the two preceding, which are 



