CHAP. XVII.] 
MAMMALIA. 
207 
Order V.— CETACEA. 
Family 36. — BALiENIDiE. (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 (Balama mys- 
tieehis). 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. — BALiENOPTERIDiE. (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) ; Fhy solus (4 species) ; and Balcenoptera 
(2 species) ; all of which have species in the North Sea. 
Family 38. — CATODONTIDiE, (4 Genera, or Sub-Genera, 
6 Species.) 
General 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 
