KEY TO THE PRINCIPAL .CETACEA 349 



dd. Size small to moderate, 5 to 10 feet. 

 Teeth 22 to 34, diameter up to \ inch. 

 e. Beak white. Teeth 22 to 25 visible in 

 each row 



White-beaked Dolphin (p. 321)- 



ec. Beak darkly pigmented. Teeth 24 to 34. 



/. Flattened diamond-shaped dark 



band on side, separate or almost 



separate from pigmentation of back. 



Lagenorhynchus Cruciger (p. 322). 

 ff. Pigmentation on side not so arranged. 

 g. A broad elongated light area on side 

 between back fin and tail en- 

 closed by darker colour. 

 h. An additional light area ante- 

 riorly on the side. 



Peale's Porpoise (p. 320). 

 hh. Pigmented portion of side not 

 enclosing light area anteriorly. 



White-sided Dolphin (p. 319). 

 gg. Two darkly coloured promontories 

 on side originating in dorsal pig- 

 mentation and projecting poste- 

 riorly. 



i. Origin of promontories in front 

 of back fin. 



Fitzroy's Dolphin (p. 324). 

 it. Origin of promontories further 

 back on flank. 



Dusky Dolphin (p. 324). 

 cc. Beak long, up to 6 inches. 



;'. Between black of back and white of belly 

 an area of undulating bands of grey, 

 yellow and white, giving impression of 

 overlapping in region behind flipper. 



Commo., Dolphin (p. 329). 

 ;;. No such overlapping of bands of colour 

 evident. 



Prodelphinns and Soialia* (pp. 331, 333)- 



* To include the species of Prodelphinus and Sotalia in the key would amount 

 to repetition of the descriptions given in the text. It is suggested therefore that 

 the reader should refer to the latter part of Chapter XV for further information 

 concerning these somewhat imperfectly known genera. 



