31 



and moUusca. Some of these the fish seemed to prefer at a 

 certain season of the year to the exclusion of the others ; thus 

 I found the ordinary univalve shellfish {Linincea stagnalis), a very 

 frequent customer during the summer months, a decided favor- 

 ite with both the Salnio foniiiialis and Salino irideus. This shell- 

 fish exists in enormous quantities in the lakes and quiet pools of 

 rivers, and is greedily devoured by the trout. They feed on 

 aquatic plants on whose stems they creep, and come occasion- 

 ally to the surface to respire. In their reproduction the same 

 limnaea is capable of serving at the same time as a male for a 

 second, and as a female for a third, and by this connection of 

 one individual with two others a continuous chain of some length 

 is not unfrequently produced. The number of eggs is pro- 

 digious, and they are deposited on stones, stems of plants, etc., 

 in elongated masses enveloped in a glary substance, very much 

 similar in appearance to that which surrounds the ova of the 

 frog. In their adult condition they love to crawl about on a 

 gravelly bottom. Other genera, such as planorbis, cytilus and 

 ancyllus, used to turn up on various occasions. These mol- 

 lusca are a valuable source of nutriment to fish, havinga double 

 function, being composed of two parts, viz. : the fleshy portion 

 or animal, which is a delicacy in itself, and its outer covering 

 or shell, which, from its containing a large proportion of 

 carbonate of lime, promotes the strength and growth of the 

 fish. 



Of Crustacea, the common fresh water sand-hopper (G^rt'w- 

 mariis pulex) was invariably to be found. It abounds in almost 

 all springs, ponds and rivulets, swimming near the bottom on 

 its side. It feeds principally on dead material, and, like the 

 limnaea, reproduces itseif in enormous quantities. As a diet, 

 it seems to cause a deeper color in the flesh of the fish. Most 

 of the larger trout like to feed on material more in proportion 

 to their size ; thus, in the summer months, the frog and tadpole 

 are particularly sought after as a bill of fare. Various species of 

 insecta both in their larval and adult conditions, worms and a 

 small brownish black leech, are also in my list of stomach 

 contents. 



Now, as an adjunct to a fish pond, it seems to me that some 



