224 THE ZOOLOGIST. 



VIII. The Indian Sea-region, or Indopelagia. 

 The Marine Carnivora, so far as we know, are entirely foreign 

 to Indopelagia, but the Sirenians are well represented by the 

 Dugong, Halicore, which pervades all its northern coasts from 

 North Australia to India and the Ked Sea, and down the African 

 coast to Lamu.* Whether the species of Halicore found at 

 different points within this area are the same or different is still 

 a matter of discussion, but there can be no doubt that Halicore is 

 an exclusive inhabitant of Indopelagia. As regards the Whales 

 of Indopelagia, we know that Physeter, Cogia, and Ziphius, and 

 numerous forms of Delphinidce, occur there ; but I am not aware 

 of any cetacean that is entirely restricted to this sea-region. 



IX. The North Pacific Sea-region, or Arctirenia. 



As was pointed out when speaking of Arctatlantis, Arctirenia 

 has one genus of Phocidce (Phoca) in common with the North 

 Atlantic, and three of the species of this genus appear to be 

 actually identical in these two sea-regions, whilst a fourth Phoca, 

 P. fasciata, is only found in the North Pacific. The Walrus, 

 Trichechus, is again a form of marine mammals common to both 

 the great northern sea-regions. But the feature of Pinnipedian 

 life that absolutely distinguishes Arctirenia from Arctatlantis is 

 the presence in the former of three (if not four) well-marked 

 species of the Eared Seals, Otariidce, which are absolutely un- 

 known in the vast extent of the Atlantic down at least to 30° S. lat. 



Arctirenia has unfortunately lost its Sirenian, Steller's Sea- 

 cow, Rhytina stelleri, the largest and finest modern representative 

 of this formerly prevalent group, which since the days of the 

 Pleistocene has greatly diminished in numbers; but I think we 

 may still treat Rhytina as one of the characteristic forms of the 

 Arctirenian sea-region. The North Pacific is also even at the 

 present day the sole possessor of a remarkable genus of Whale- 

 bone Whales which combines the long head and elongate form of 

 Balcenoptera with the smooth skin of the throat and absence of 

 the dorsal fin of Balana.\ This is the Grey Whale, Rhachia- 



* A fine specimen of the Dugong from Lamu (on the east coast of 

 Africa, lat. 2° 50' S.), obtained by Mr. J. C. Haggard in 1885, is in the 

 British Museum. 



f Flower and Lydekker, ' Mammals,' p. 241. 



