REPTILES, BATRi^CHIANS, AND FISHES. 47 



No opportunity should be lost to obt liri jyelagic forms, especially 

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

 of the open ocean. They can be obtained without difficulty by means 

 of a small narrow- meshed neb 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 

 neb 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 passiag 

 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 fioating 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 Ghilodactylus of the Southern Seas, the Tunnies and 

 Swprd-:Sshes of the Indo-f acific, the Salmonids, the Clupeids, etc, 



