MARINE MAMMALS 213 



This is the Grey Whale, Rhachianeetes glaucus of Cope, 

 which, in these days, is confined to the North Pacific, 

 and does not range farther south than the 20th parallel 

 in that ocean. At the same time it should be stated that 

 indications have been discovered that a nearly allied form 

 existed in the Atlantic in previous geological ages, though 

 this is by no means certain. Besides Rhachianeetes, 

 Balama, Megaptera, and Balamoptera are all represented 

 in the North Pacific, and also many species of Delphinidze 

 of which little is at present known. But Rhytina and 

 Rhachianeetes are the only genera of Marine Mammals 

 absolutely confined to Arctirenia. 



Section X. — The Mid-Pacific Sea-region, 

 or Mesirenia 



The Eared Seals, Otaria, must have necessarily passed 

 through Mesirenia in their passage from south to north, 

 though the only record of their actual presence in the 

 central part of the Pacific is, so far as we know, the recent 

 discovery of them in the Galapagos. It should be stated, 

 however, that Tschudi records the occurrence of two 

 species of Otaria on the islands of the coast of Peru, and 

 that in 1802 Humboldt met with an Eared Seal on the 

 Island of San Lorenzo, in the Bay of Callao, which is only 

 some 12° south of the Equator. 



Like Otaria, the Sea-elephant (Macrorhinus) has appa- 

 rently in former ages travelled up the South American 

 shores and established itself as far north on the coast of 

 California as about 34° N. lat. The Calif ornian Sea- 

 elephant has been discriminated by Gill as a distinct 



