Protozoa and Rotifera. at Ilarana, III. 



313 



pelagic were those that evidently preferred clear open water, 

 free from vegetation. 



Thirty-five of the species here treated were found in open 

 water, either in surface, hottom, or oblique towings. They 

 are as follows : 



Arcella vulgaris Ehrl)g. 

 Arcella vulgaris discoides 



Leidy. 

 Arcella vulgaris angulosa 



Leidy. 

 Arcella dentata Ehrbg. 

 Difflugia globulosa Duj. 

 Difflugia pyriformis Perty. 

 Difflugia acuminata Ehrbg. 

 Difflugia lobostoma Leidy. 

 Difflugia corona Wallich. 

 Difflugia aculeata Ehrbg. 

 Difflugia tuberculosa 



Hempel. 

 Difflugia fragosa n. sp. 

 Actinophrys sol Ehrbg. 

 ActinospluTerium eichhornii 



Ehrl)g. 

 Eaphidiophrys pallida 



Schulze. 

 Dinobryon sertularia Ehrbg. 

 Euglena viridis Ehrbg. 

 Euglena spirogyra Ehrbg. 



Euglena acus Ehrbg. 

 Euglena oxyuris Schmarda. 

 Euglena torta Stokes. 

 Trachelomonas acuminata 



Schmarda. 

 Phacus longicauda Ehrbg. 

 Phacus pyrum Ehrbg. 

 Volvox globator Ehrbg. 

 Pleodorina californica Shaw. 

 Cryptomonas ovata Ehrbg. 

 Peridinium tabulatum Ehrbg. 

 Ceratium brevicorne Hempel. 

 Paramecium aurelia 0, F. 



Mull. 

 Stentor polymorphus 0. F. 



Mull. 

 Stentor cieruleus Ehrbg. 

 Stentor barretti Barrett. 

 Halteria grandinella 0. F. 



MiUl. 

 Codonella crateia Leidy. 

 Tintinnopsis illinoisensis 



Hempel. 



To these might be added Didinhim )tasuti(iii 0. F. IMiilL, 

 mentioned by Zacharias ('94a), and Trachelomonas caudata 

 Ehrbg, both of which were found in aquaria started with mud 

 from the bottom of Phelps Lake. 



One peculiar fact noted was the occurrence of a number of 

 Rhizopoda in the surface towings. Prof. Frank Smith ('94) 

 lists three species as occurring in surface collections in Lake 

 St. Clair; Dr. C. A. Kofoid lists eight species from the waters 



