REPTILES, BATRACMANS, AND FISHES. 
45 
No opportunity should be lost to obtain pelagic forms, especially 
the young larvalike stages of development abounding on the surface 
of the open ocean. They can be obtained without difficulty 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 pass- 
ing into the strong main line. It can only be used when the vessel 
moves very slowly, the speed not exceeding 3 knots an hour, or when 
a current passes the ship whilst at anchor. To keep the ring of the 
net in a vertical position, it must 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 in the daytime, as many fishes 
come to the surface only after sunset. The net must not be left 
long in the water, from five to twenty minutes only, as delicate 
objects are sure to be destroyed by the force of the water passing 
through the meshes. 
By the examination of the contents of the stomachs of large fishes 
(Tunnies, Dolphins, etc.) caught in the open sea, rare forms can be 
discovered. Objects found floating on the open sea, such as pieces 
of wood, baskets, larger or smaller masses of weed, etc., deserve the 
collector's attention, as small fishes and marine creatures of all kinds 
generally swarm round them. Shallow banks situated at a consider- 
able distance from land are likely to yield a valuable store of fishes 
of all kinds, which may be obtained either with hook and line or with 
the above-described fish-baskets. 
The latitude and longitude should be carefully noted in the case 
of all specimens obtained in the open sea. 
It may be useful to conclude these instructions with drawing the 
attention of the traveller to a few points on which information is 
particularly desired. 
Important information may be gathered relating to fishes which 
either are actually used as food (fresh or for exportation) or which 
may become an important article of trade. The following fishes, there- 
fore, deserve special attention : the Sturgeons, the species of Gadus, 
the Thyrsites, the Chilodactylus of the Southern Seas, the Tunnies and 
Sword-fishes of the Indo-Pacific, the Salmonids, the Clupeids, etc. 
