DOLPHIKS, PORPOISES. 343 



seas, especially the north and south temperate, aad exhibit a marked 

 specific identity between the most widely removed forms (Australia 

 and North Atlantic). The type of the genus h the pilot-whale (G. 

 melas ; Delphinus globiceps), the grindhval of the Faroe-Islanders, 

 whose distribution is practically coextensive with the northern seas. 

 Related to the preceding are the so-called grampuses of the genus 

 Grampus, of which only one species (G. griseus), remarkable for the 

 variability of its colouring, has been thus far clearly determined ; it 

 inhabits the northern ocean, more rarely descending into the Medi- 

 terranean, A second form, from the Cape of Good Hope, has been 

 described as G. Tlichardsoni. 



The true grampuses, also known as " killers," from their preda- 

 cious habits, constitute the genus Orca, and are more nearly related 

 to the true porpoises than to the dolphins proper. They are dis- 

 tributed over the greater portion of the oceanic expanse, from Green- 

 land to Tasmania ; but neither the relationships of the different so- 

 called species, nor the limitations of their respective habitats, have 

 as yet been determined. Orca gladiator, the common grampus, is 

 more properly a northern form, and is fairly abundant in the polar 

 seas. Pseudorca crassidens, a much rarer form of grampus, found 

 on the Danish coast, appears to be identical with a species from the 

 Australian waters. The genus Orcella is represented by two species, 

 one of which (O. brevirostris) inhabits the Bay of Bengal, and the 

 other (O. fluminalis), a fluviatile form, the Irrawaddy River, at a 

 distance of several hundreds of miles from its mouth. 



Of the true porpoises of the genus Phocgena, whose limited 

 species are confined principally to the waters of the Northern 

 Hemisphere,* the best known and probably most widely distributed 

 form is P. communis, the common porpoise, which inhabits in 

 shoals or schools the North Atlantic, from Britain to Greenland 

 and the American coast, frequently ascending the outflowing 

 streams for a considerable distance above their mouths. They 

 have been observed on the Thames, at London, and appear to 

 have occasionally penetrated up the Seine as far as Paris. The 

 animal does not seem to enter the Mediterranean. By some natu- 

 ralists the common porpoise of the Atlantic coast of the United 

 States is considered to be a distinct species, to which the name P. 



* Phocaena spinipennis has been described from the mouth of the Eio de 

 la Plata. 



