May U, 1897.] 



SCIENCE. 



747 



the southern form (il/. leonimis) 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 

 oi Meyaptera, Balcenojytera, Physeter, Cogia und 

 Ziphius certainly occur there, besides many 

 representatives of the widely spread Del- 

 phinidai. 



XI. THE SOUTHERN POLAR SEA-EEGION, OE 

 NOTOPELAGIA. 



The wide ocean which sui-rounds the 

 Southern Pole on every side, and extends 

 up to 40° S. lat., seems to present, as re- 

 gards its marine mammals, a nearly homo- 

 geneous fauna, which we will now briefly 

 consider. In the first place it contains I'ep- 

 resentatives of four genera of true Phocidce 

 — Ognovhinus, Lobodon, LeptonycJiotes,^^ and 

 OmmntopJioca, which are peculiar to the 

 southern seas, and are quite distinct from 

 all their northern representatives in the 

 Arctic Ocean. The Sea-elephant, Macro- 

 rhinus, 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 Macrorliinits, Otaria also, containing 

 the group of Eared Seals, appears to have 

 been an Antarctic group, and the greater 

 number of its species, although now-a-days 

 very much reduced in numbers, are still 

 found in the Southern Ocean. But the 

 Otarice have travelled still further north 

 than Macrorhimis, and three, if not four, 

 species, as already stated, are in these days 

 well established inhabitants of Arctirenia. 



The Sirenians are absent from Notope- 

 lagia, but Cetaceans of every kind are abun- 

 dant. Besides one or more representatives of 

 the true Whale-bone Whale (Bala'na),'No- 



* This generic term, establisbed by Gill in 1873, 

 seems to take precedence of Pmcilophoca, proposed by 

 Flower and Lydekker for the same type (L. wethUlU) 

 in 1891. Cf. Allen, North American Pinnipeds, p. 

 418. 



topelagia has a smaller representative of the 

 group (Neobcdmna) entirely restricted to its 

 area. It has also representatives of Meg- 

 aptera and Bcdccnoptera, though it is doubt- 

 ful how far they are even specifically dis- 

 tinct from some of their northern repre- 

 sentatives. 



Among the Toothed Whales ( Odontoceti) 

 we find a large Ziphioidform, Berardius, re- 

 stricted to the Notopelagian area, while 

 Ziphius and Mesopdodon also occur there. 

 The Dolphins (Delphinldce) are likewise 

 numerous and present some distinct species, 

 but not, so far as our present knowledge ex- 

 tends, any generic forms that do not occur 

 elsewhere. 



But ISTotopelagia is sufficiently distin- 

 guished from all the five more northern 

 Sea-regions by possessing four genera of 

 Seals and two of Cetaceans entirely re- 

 stricted to its area. 



XII. CONCLUSIONS. 



It has, therefore, I think, been shown that 

 for the Geography of Marine Mammals the 

 Ocean may be most conveniently divided 

 into six Sea-regions, which are as follows : 



I. Reglo Arctatlantica, characterized by its 

 Seals {Phociuce), of which two genera, Hali- 

 duerus and Cijdophora, are peculiar, whilst 

 Phoca is common to it and Arctirenica ; by 

 the absence of Sirenians ; and by the pos- 

 session of three peculiar genera of Ceta- 

 ceans (Hypei-oodon, Delphinapteius and Mono- 

 don) . 



II. Reglo ilesatlantica, sole possessor of the 

 Monk-seal, Monachus, amongst the Pinni- 

 peds, and of the Sireniau genus Manatus. 



III. Regio Iiulopelagica, characterized by 

 the presence of the Sirenian Halicore and by 

 the absence of Pinnipeds. 



IV. Regio Arctirenica, with Phoca, like the 

 Regio Arctatlantica, but having Otaria also ; 

 the home of the (now extinct) Sirenian 

 Rhytina and of the endemic Cetacean Rhachi- 

 anectes. 



