546 



SCIENCE, 



[N. S. Vol. XIV. No. 354. 



on the mainland of Asia, from which region 

 all of them were originally derived. 



FRESH-WATER FATJNAL AREAS. 



Two faunal areas of fresh waters may be 

 fairly distinguished, although broadly over- 

 lapping. The northern region includes the 

 island of Hokkaido and the middle and 

 northern part of the great island of Hondo. 

 In a rough way, its southern boundary may 

 be defined by Fuji Yama and the Bay of 

 Matsushima. It is characterized by the 

 presence of salmon, trout and sculpins, and 

 northward by sturgeon and brook-lampreys. 

 The southern area loses by degrees the 

 trout and other northern fishes, while in 

 its clear waters abound various minnows, 

 gobies and the famous ayu, or Japanese 

 dwarf salmon, one of the most delicate of 

 food fishes. Sculpins and lampreys give 

 glace to minnows, loaches and chubs. 

 Two genera, a sculpin* and a perch,f are 

 confined to this region and seem to have 

 originated in it, but like the other species, 

 form a Chinese stock. 



ORIGIN OP JAPANESE FRESH-WATER FISHES. 



The question of the origin of the Japan- 

 ese river fauna seems very simple. All 

 the types are Asiatic. While most of the 

 Japanese species are distinct, their ances- 

 tors must have been estrays from the main- 

 land. To what extent river fishes may be 

 carried from place to place by currents of 

 salt water has never been ascertained. 

 One of the most widely distributed of 

 Japanese river fishes is the large hakone 

 dace or chub. | This has been repeatedly 

 taken by us in the sea at a distance from 

 any stream. It would evidently survive a 

 long journey in salt water. An allied 

 species § is found in the midway island of 

 Tsushima, between Korea and Japan. 



* Trachidermis. 



t Bryitosus. 



X Leuciscus kakuensis Giinther. 



^ Leuciscus jouyi. 



FAUNAL AREAS OF MARINE FISHES. 



The distribution of the marine fishes of 

 Japan is mainly controlled by the tempera- 

 ture of the waters and the motion of the 

 ocean currents. Five faunal areas may be 

 more or less clearly recognized, and these 

 may receive names indicating their scope, 

 Kurile, Hokkaido, Nippon, Kiusiu, Kuro 

 Shi wo and E,iu Kiu. The first or Kurile 

 district is frankly sub-Arctic, containing 

 species characteristic of the Ochotsk Sea 

 on the one hand, and of Alaska on the 

 other. The second or Hokkaido* dis- 

 trict includes this northern island and that 

 part of the shore of the main island of 

 Hondo f which lies to the north of Mat- 

 sushima and Noto. Here the cold north- 

 ern currents favor the development of a 

 northern fauna. The herring and the sal- 

 mon occupy here the same economic rela- 

 tion as in Norway, Scotland, Newfound- 

 land and British Columbia. Sculpins, 

 blennies, rockfish and flounders abound 

 off" the rocky shores and are seen in all the 

 markets. 



South of Matsushima Bay and through 

 the Inland Sea as far as Kobe, the Nippon 

 fauna is distinctly one of the temperate 

 zone. Most of the types characteristically 

 Japanese belong here, abounding in the 

 sandy bays and about the rocky islands. 



About the islands of Kiusiu and Shikoku, 

 the semi-tropical elements increase in num- 

 ber and the Kiusiu fauna is less character- 

 istically Japanese, having much in common 

 with the neighboring shores of China, while 

 some of the species range northward from 

 India and Java. But these faunal districts 

 have no sharp barriers. Northern fishes, J 

 unquestionably of Alaskan origin, range as 

 far south as Nagasaki, while certain semi- 



* Formerly, but no longer, called Yeso in Japan. 



f Called Nippon on foreign maps, but not so in 

 Japan, where Nippon means the whole empire. 



"I Pleuronichthys cornutus ; Hexagrammos otakii ; 

 Ozorthe Jiexa gramma, etc. 



