286 



FEESH-WATEH, AQUAEIA. 



The little crustacean sometimes called the "Fresh-water 

 Screw," or Shrimp {Gammarua flvAiiatilia) (Fig. 166), is a use- 

 ful and interesting inmate of the aquarium. It may be found 

 in almost every clear and not very quick-running stream. 



Fig. 156. Fresh-water Shrimps (Gammarus pluviatilis) (enlarged). 



but especially in those brooks in which the watercress or the 

 Vernal Starwort grow in anything like profusion. A good 

 way to obtain Fresh-water Shrimps is to take a handful of 

 aquatic weeds out of the water in which these Crustacea 

 abound, and shake it over a newspaper or a piece of macintosh. 

 After the first shake or two, several Shrimps, among other 



