266 A BOOK OF~WHALES 



four last cervicals free. Six of the ribs are two- 

 headed ; but as few as five, and as many as seven, 

 may be so.* 



Lagenorhynckus obliquidens, Gill, t may be distin- 

 guished in the following terms :-- Length, 7 feet 

 some inches. Colour, greenish black above, with 

 lateral broad longitudinal stripes of white-grey and 

 dull black; white below. Teeth, 31. Vertebrae: C. 

 7; D. 13; L. 24; Ca. 30 = 74. Pterygoids not in 

 contact, divergent posteriorly. 



This is a North Pacific species of exceeding 

 activity. It congregates in herds of many hundreds, 

 "tumbling over the surface of the sea, or making 

 arching leaps, plunging again on the same curve, or 

 darting high and falling diagonally sideways upon 

 the water with a spiteful splash, accompanied by a 

 report that may be heard at some distance. When 

 a brisk breeze is blowing they frequently play about 

 the bow of a ship going at her utmost speed, darting 

 across the cut-water and shooting ahead, or circling 

 around the vessel, apparently sporting at ease." 

 These porpoises feed upon small fish, and, says 

 Scammon, act up to their character of the "sea 

 swine," filling themselves to repletion. As with 

 other dolphins, these animals will collect in calm 

 weather in immense herds, huddled together on the 

 surface of the water. 



* LiiTKEN, "Critical Studies upon Odontoceti," Ann. Mag. Nat. 

 Hist. (2), xii., 1888, p. 179. 



t P. A cad. Nat. Sci. Philadelphia, 1865, p. 177. 



