October 11, 1901.] 



SCIENCE. 



547 



tropical * types extend their range north- 

 ward to Hakodate and Volcano Bay. The 

 Inland Sea, which in a sense bounds the 

 southern fauna, serves at the same time as 

 a means of its extension. While each species 

 has a fairly definite northern or southern 

 limit, the boundaries of a faunal district as 

 a whole must be stated in the most general 

 terms. 



The well-known boundary called Blackis- 

 ton's Line, which passes through the Straits 

 of Tsugaru, between the two great islands 

 of Hondo and Hokkaido, marks the north- 

 ern boundary of monkeys, pheasants and 

 most tropical and semi-tropical birds and 

 mammals of Japan. But as to the fishes, 

 either marine or fresh water, this line has 

 no significance. The northern fresh-water 

 species probably readily cross it ; the south- 

 ern rarely reach it. 



We may define as a fourth faunal area 

 that of the Kuro Shi wo district itself, which 

 is distinctly tropical and contrasts strongly 

 with that of the inshore bays behind it. 

 This warm ^ Black Current,' analogous to 

 our Gulf Stream, has its origin in part from 

 a return current from the east, which passes 

 westward through Hawaii, in part from a 

 current which passes between Celebes and 

 New Guinea. It moves northward by way 

 of Luzon and Formosa, touching the east 

 shores of the Japanese islands Kiusiu and 

 Shikoku, to the main island of Hondo, 

 flooding the bays of Kagoshima and Kochi, 

 of Waka, Suruga and Sagami. The 

 projecting headlands reach out into it 

 and the fauna of their rock pools is dis- 

 tinctly tropical, as far to the northward as 

 Tokio. 



These promontories of Hondo, Waka, 

 Ise, Izu, Misaki and Awa have essentially 

 the same types of fishes as are found on the 

 reefs of tropical Polynesia. The warmth 

 of the off-shore currents gives the fauna of 



* As Halichoeres, Tetrapturus, Callionymus, Aris- 

 copus, etc. 



Misaki its astonishing richness, and the 

 wealth of life is by no means confined to 

 the fishes. Corals, crustaceans, worms 

 and molluscs show the same generous pro- 

 fusion of species. 



A fifth faunal area, closely related to 

 that of the Black Current, is formed by the 

 volcanic and coral reefs of the Riu Kiu 

 Archipelago. This fauna, so far as known, 

 is essentially East-Indian, the genera and 

 most of the species being entirely identical 

 with those of the islands about Java and 

 Celebes. 



RESEMBLANCE OF THE JAPANESE AND 

 MEDITERRANEAN FISH FAUNAS. 



It has been noted by Dr. Giinther that 

 the fish fauna of Japan bears a marked 

 resemblance to that of the Mediterranean. 

 This likeness is shown in the actual identity 

 of genera and species, and in their relation 

 to each other. This resemblance he pro- 

 poses to explain by the hypothesis that, at 

 some recent period, the two regions, Japan 

 and the Mediterranean, have been united 

 by a continuous shore-line. The far-reach- 

 ing character of this hypothesis demands 

 a careful examination of the data on which 

 it rests. 



The resemblance of the two faunal areas, 

 so far as fishes are concerned, may be stated 

 as follows : There are certain genera * of 

 shore fishes, tropical or semi-tropical, com- 

 mon to the Mediterranean and Japan, and 

 wanting to California, Panama and the 

 West Indies, and in most cases to Poly- 

 nesia also. Besides these, certain others, 

 found in deeper water (100 to 200 fathoms) 

 are common to the two areas,f and have 

 been rarely taken elsewhere. 



* Of these, the principal ones are Oxystomus, Sfyrus, 

 Pagrus, Sparus, Macrorhamphosus, CepoJa, CaUionyinus, 

 Zeus, Uranoscoims, Lepidotrigla, Chelidonichthys . 



f Among these are Beryx, Helicolenus, Lotella, Net- 

 teuitoma, Centrolophus, Hoplostethus, Aulopus, Chloroph- 

 thalmus, Lophotes. 



