704 DIEECTIONS 



A few remarks may be added as regards those Faunae, which 

 promise most results to the explorer, with some hints as to 

 desirable information on the life and economic value of fishes. 



It is surprising to find how small the number is of the fresh- 

 water fauniB which may be regarded as well explored ; the rivers 

 of Central Europe, the Lower Nile, the lower and middle course 

 of the Ganges, and the lower part of the Amazons are almost the 

 only fresh waters in which collections made without discrimina- 

 tion would not reward the naturalist. The oceanic areas are 

 much better known ; yet almost everywhere novel forms can be 

 discovered and new observations made. Most promising and 

 partly quite unknown are the following districts : — the Arctic 

 Ocean, all coasts south of 38° lat. S., the Cape of Good Hope, 

 the Persian Gulf, the coasts of Australia (with the exception of 

 Tasmania, New South Wales, and New Zealand), many of the 

 little-visited groups of Pacific islands, the coasts of north-eastern 

 Asia north of 35° lat. N., and the western coasts of North and 

 South America. 



No opportunity should be lost to obtain pelagic forms, especi- 

 ally the young larva-like stages of development abounding on the 

 surface of the open ocean. They can be obtained without diffi- 

 culty by means of a small narrow meshed net dragged behind 

 the ship. The sac of the net is about 3 feet deep, and fastened 

 to a strong brass-ring 2 or 2|- feet in diameter. The net is 

 suspended by three lines passing into the strong main line. It 

 can only be used when the vessel moves very slowly, its speed' 

 not exceeding three knots an hour, or when a current passes the 

 ship whilst at anchor. To keep the net in a vertical position 

 the ring can be weighted at one point of its circumference ; and 

 by using heavier weights two or three" drag-nets can be used 

 simultaneously at different depths. This kind of fishing should 

 be tried at night as well as day, as many fishes come to the 

 surface only after sunset. The net must not be left long in the , 

 water, from 5 to 20 minutes only, as delicate objects would be 

 sure to be destroyed by the force of the water passing through 

 the meshes. 



Objects found floating on the surface, as wood, baskets, sea- 

 weed, etc., deserve the attention of the travellers, as they are 

 generally suiTounded by small fishes or other marine animals. 



