536 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



canus, hrasiliensis ; that is, 19 genera, with 44 species, in the average 

 two species for every genus.* 



In the Pacific Ocean the Gadidce are distributed : on the west coast of 

 North America to San Francisco, and of South America to Chili, and 

 on the east coast of Asia from Behring Strait to Northern China, 

 Chusan and by way of the Philippines to the mouth of the Ganges, and 

 farther southward to New Zealand, not, however, as a connected series. 

 The following are the genera and species : Gadus morrJiua, minutus, call- 

 fornicus, productus, macrocepJialus, chalcogrammus ; Merlucius Gayi; 

 Motella pacijica ; Lotella phyois, rkacimis, bacchus ; Pseudopliycis hrevius- 

 cuius; Bregmaceros Maclellandii ; that, is 6 genera with 13 species. The 

 number of genera and species in the same ratio as in the Atlantic Ocean. 



We shall now discuss more in detail the natural relations and tHe 

 distribution of the genera and species in those three oceanic basins. 



C— THE AECTIC EEGION OF THE GADID^. 



Between the two large continental masses of the Old and the New 

 "World and almost entirely surrounded by them a great body of water 

 is situated, which forms an immense inland sea of 1,826,000 square miles. 

 This enormous sea is the basin of the Arctic and Atlantic Oceans. 

 That these two oceans naturally form but one, is shown by the three 

 connecting straits, whose breadth averages from, respectively 40 to 120 

 miles, while the Pacific Ocean has but one connection with the Arctic, 

 the narrow Behring Strait. This great sea is naturally subdivided 

 into three smaller basins, the Arctic, the North and the South Atlantic 

 Oceans. The North Atlantic Ocean is connected with the Arctic and 

 with the South Atlantic Ocean. The North Atlantic is, therefore, more 

 particularly subject to the influence of the Arctic Ocean, while the latter, 

 too, is influenced by the former, and this in return by the South Atlantic. 

 'The line of division of these three basins cannot be defined, as their 

 natural characteristics are frequently blending with each other. The 

 Arctic and North Atlantic Oceans are extraordinarily rich in large and 

 small islands, between which straits and channels run, and they have 

 numberless creeks, fiords, bays, and many inland seas of different size. 

 Many and large rivers carry quantities of fresh water, sand, and detritus 

 into these seas, and so form lagoons. 



In consequence of this exceedingly rich development of the coast 

 region the formation of fresh-water ice is favored, which, however, melts 

 rapidly on account of the warm current from the South Atlantic Ocean, 

 thus supplying, in conjunction with the rivers, the sea largely with wide 

 and deep strata of fresh water. 



The temperature, saltness, amount of food, currents, and depth of the 

 sea are essential conditions for the distribution. The Arctic Ocean has, 

 even in midsummer, according to Martins, a somewhat higher temper- 

 ature at its surface than the air, in consequence of the Gulf Stream, 



* Add Phycis tinuis, (Mitcb.) DeKay. Two new species, Haloporpliyriis viola and 

 Phycia Chcstei'i, have recently been discovered in the southern region by the United 

 States Fish Commission. 



