342 Illinois State Laboratory of Natural History. 



It occurred principally in May and June, in collections from 

 a number of substations, and was usually found associated 

 with Epistylis plicatilis and Opercidaria irritabilis, attached 

 to small animals taken among vegetation. It is recorded 

 from Cambarus diogenes, C. blandingii acutus, Chelydra ser- 

 pentina, Aromochelys odoratus, and larvae of Hexagenia. 



AciNETA Ehebg. 



Solitary, ovate or elongated, basally or entirely within a 

 cup-like lorica with a rigid pedicel ; reproduction as in Toko- 

 jthrya. 

 93. A. mystacina Ehrbg. 



In the aquaria started with dried mud from Phelps Lake 

 this species was quite common. It is very voracious, living 

 upon Ciliata. Several specimens were observed while thus 

 eating, and the passage of food particles through the tentacles 

 was easily seen. 



ROTIFERA. 



The researches and investigations of morphologists during 

 recent years have led to a clearer and fuller acquaintance 

 with the details of animal structure, thus stimulating study 

 along related lines. The field of the systematist has thus 

 been broadened and extended. With a thorough knowledge 

 of the anatomy of the animal body rather than a mere ac- 

 quaintance with its external appearance, he is now better able 

 to trace the relationships of the various subdivisions of the 

 animal kingdom, and to place each form in the group to 

 which it properly belongs. At the same time has come the 

 study of cecology — the relation of organisms to each other 

 and to their environment. Nothing can be more fascinating, 

 or of more value in solving the general problems of life than 

 this study of interrelations and dependences ; but it cannot 

 be carried on rightly unless our knowledge of the morphology, 

 habits, etc., of the forms under observation is as complete as 

 science can make it. Nor should this study be confined 

 solely to animals of large size and easy of access ; it must be 



