4 U. S. BUREAU OF FISHERIES. 



were so common and of such wide distribution that a supply, as a 

 rule, was conveniently available. 



The principal advocates of the culture of crustaceans Avere Euro- 

 pean fish-culturists. In this country the idea had its supporters, 

 although there were others who had no faith in it. The latter took 

 the ground that while, owing to the small number of fishes raised, 

 culture of crustaceans as food for young fishes Avas practicable in 

 European establishments, in this country, where the business is con- 

 ducted on a much larger scale, it would be impossible to maintain 

 a sufficient supply to feed the fish. 



There can be no doubt that these crustaceans would afford a most 

 valuable food supply for young fishes if their culture should prove 

 practicable on a scale to meet the demand, for some of the smaller 

 kinds form, under natural conditions, the principal food of almost 

 all species of young fishes and almost the entire food supply of some 

 adult small species, which in turn form the food of some adult large 

 species, the young of which subsist largely upon the crustaceans. 



If a system of crustacean culture can be devised which will meet 

 the demand of the fish-culturist and the fish farmer, it will be a boon 

 of inestimable importance. This paper does not pretend to devise 

 such a system, but by reviewing what has been done and by afford- 

 ing some information regarding the nature, distribution, and habitats 

 of the little animals concerned, it is hoped that it may afford the 

 foundation, or at least the corner stone, of the desired structure. 

 Most of the information conveyed by this paper is derived from a few 

 special works. The greater part of that pertaining to the habits of 

 the lower forms is derived, sometimes verbatim, from Ward and 

 Whipple's Fresh-Water Biology, in which the subject of Phyllopoda 

 is treated by A. S. Pearse, of Cladocera by Edward A. Birge, of 

 Copepoda by C. Dwight Marsh, of Ostracoda by R. W. Sharpe, and 

 of Malacostraca by A. E. Ortmann. Most of the matter pertaining 

 to the Amphipoda, belonging to the latter class, however, must be 

 credited to George C. Embody. 



A list of the publications to which reference is made and credit 

 given is appended. The date corresponds to that in parentheses 

 following the author's name in the text of this paper. 



CRUSTACEA. 



TTor convenience the crustaceans with which this paper is con- 

 cerned may be classed as (1) Entomostraca and (2) Malacostraca. 



ENTOMOSTRACA. 



The Elntomostraca are very small, and some are so very minute as 

 to be quite invisible to the naked eye. They enter largely into the 

 natural food supply of the youngest stages of various fishes and 

 even adults of some fishes. 



The entomostracan class is subdivided into three distinct groups, 

 designated as follows: Branchiopoda, Ostracoda, and Copepoda. 

 Branchiopod is a name derived from the fact that the little animals 

 have respiratory organs or gills attached to their " feet." Branchi- 

 opoda comprise two groups, Phyllopoda and Cladocera which for 

 our purposes will be treated separately. 



