1897.] DlSTRiBtTTlOK OF MARIIJ-E MAMMALS. 355 



in the Mediterranean and on the North African coast, and a second 

 (M. tropkalis) being found in the West Indies. Mesatlantis is like- 

 wise the true home of the well-marked Sirenian genus Manatus, 

 one species of which {M. americanus) frequents the coast of 

 America and another {M. senegalensis) that of Africa. 



As regards the Cetaceans, we are not able to say that Mesatlantis, 

 although well-furnished with many generic types of this Order, has 

 any one peculiar to it. AVe must therefore rest content with 

 assigning two genera of Marine Mammals, Monachus&nA.Manat'us, 

 as characteristic forms or toporaorphs of the Sea-Mammal-life of 

 Mesatlantis. 



VIII. The Indian Sea-rerjion, or Indopelagia. 



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

 to Indopelagia, but the Sirenians are well represented by the 

 Dugong {Halicore), which pervades all ii^s northern coasts from 

 North Australia to India and the Eed 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 Zipliius, and numerous forms of 

 Delphinicla 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 Phoclclie {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 AValrus (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 xirctirenia from Arctatlantis is the presence 

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

 Eared Seals {Otariidoi), which are absolutely unknown in the vast 

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



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

 {Rhijtina stelleri), the largest and finest modern representative of 

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

 cene 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 Whalebone Whales which 

 combines the long head and elongate form of Balamoptera with 

 the smooth skin of the throat and absence of the dorsal fin of 

 Balcena^. This is the Grey Whale, Ehachiaaecfes glaucus of Cope, 



1 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. 

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



