NAIDID^ OF CEDAR POINT, OHIO* 



The microscopic annelids constituting the family 

 Naididas of the subclass Oligochaeta are a group which has 

 received little attention in America. Michaelsen (:00) 

 in his monograph of the Oligochaeta recognized 42 species 

 from various parts of the world and of that number only 

 6 were noted as occurring in our territory although obser- 

 vations made by Smith (:00) and noted in the appendix 

 ("Zusatze und Berichtigungen") increased the number to 

 12. While this, taken in connection with the fact that 

 the observations have been confined almost entirely to two 

 localities, the one in Pennsylvania the other in Illinois, 

 furnishes sufficient justification for a review of the 

 Naididas occurring at Cedar Point, Ohio, some contem- 

 plated studies of a statistical nature rendered a preliminary 

 survey of several groups of fresh water organisms desirable 

 for the purpose of ascertaining which could be used most 

 advantageously in the problems under consideration. 

 Consequently the present paper is purely from a system- 

 atic standpoint, and although a considerable number of 

 specimens have been fixed, stained, and mounted, and a 

 few imbedded and sectioned, no attention beyond that 

 necessary to differentiate the species has been given to 

 anatomical or histological structure. 



In addition to the interest attached to the study of these 

 organisms upon the side of pure science, as outlined above, 

 the fact that they play a role of decided economic im- 

 portance must not be overlooked. The relation of the 

 microscopic organisms or "plankton," accepting the defi- 

 nition in its broadest sense, to the distribution of food 

 fishes is a subject which has received increasing attention 

 during the past twenty years. Inasmuch as the food of 

 fishes is made up chiefly of small Crustacea, insect larv*e, 

 minnows, etc., the existence of these being in turn depend- 



*Reprinted from The American Naturalist, vol. 40 (1906), pp. 683-706. 



