OCR Text |
Show 356 MR. P. L. SCLATER ON T H E [Mar. 16, which, in these days, is confined to the North Pacific, and does 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 Rhachianectes, Balcena, Megaptera, and Balcenoptera are all represented in the North Pacific, and also many species of Delphlnldce of wdiich little is at present known. But Rhgtina and Rhachianectes are the only genera of Marine Mammals absolutely confined to Arctirenia. 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 I know, tbe 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 Sau Lorenzo, in the Bay of Callao, which is only some 12° south of the Equator. Like Otaria, the Sea-elephant (Macrorhinus) has apparently in former ages travelled up the South American shores and established itself as far north on the coast of California at about 34° N. lat. The Californian Sea-elephant has been discriminated by Gill as a distinct species (Macrorhinus angustirostris), but its differences from tbe southern form (M. leoninus) seem to be but trifling. As regards the Cetaceans of Mesirenia, our information is at present very imperfect, and I have little to say except that species of Megaptera, Balcenoptera, Physeter, Cogia, and Ziphius certainly occur there, besides many representatives of the widely spread Delphlnldce. XI. Tlie Southern Polar Sea-region, or Notopelagla. The wide ocean which surrounds the Southern Pole on every side, and extends up to 40° S. lat., seems to present, as regards its marine mammals, a nearly homogeneous fauna, which we will now briefly consider. In the first place it contains representatives of four genera of true Phocldce-Ogmorhinus, Lobodon, Leptonychot.es1, and Ommatophoca, which are peculiar to the southern seas, and are quite distinct from all their northern representatives in the Arctic Ocean. The Sea-elephant, Macrorhinus, is also a denizen of Notopelagia, though, as we have already seen, it has wandered north along the South American coast far into Mesirenia. Like Macrorhinus, Otaria also, containing the group of Eared 1 This generic term, established by Gill in 1872, seems to take precedence of Pmcilophoca, proposed by Flower and Lydekker for tbe same type (L. wed-delli) in 1891. Cf. Allen, North American Pinnipeds, p. 418. |