COLLECTION OF MINUTE CRUSTACEANS. 651 



which are developed into Chelce or pincers ; and the little creature 

 entirely loses the active swimming habits which it originally pos- 

 sessed, and takes-on the mode of life peculiar to the adult. 



509. In collecting minute Crustacea, the Ring-net should be 

 used for the Fresh-water species, and the Tow-net for the Marine. 

 In localities favourable for the latter, the same ' gathering ' will 

 often contain multitudes of various species of Entomostraca, ac- 

 companied, perhaps, by the larvae of higher Crustacea, by Echino- 

 derm-larvae, by Annelid-larvae, and by the smaller Medusae. The 

 water containing these should be put into a large Glass Jar, freely 

 exposed to the light ; and after a little practice, the eye will 

 become so far habituated to the general appearance and modes of 

 movement of these different forms of Animal life, as to be able to 

 distinguish them one from the other. In selecting any specimen 

 for Microscopic examination, the Dipping-tube (§ 100) will be 

 found invaluable. If the Collector should happen to gather any 

 floating leaves of Zostera, he will do well to examine these for 

 Megalopa-]&rv?e, which the Author has frequently found clinging 

 to their surfaoe, his attention being directed to them by the bright- 

 ness of their two black eye-spots. — The study of the Metamor- 

 phosis will be best prosecuted, however, by obtaining the fertilized 

 Eggs which are carried-about by the Females, and watching the 

 history of their products. — For preserving specimens, whether of 

 Entomostraca, or of Larvae of the higher Crustacea, the Author 

 would recommend Glycerine -Jelly as the best medium. 



