314 Illinois State Laboratorfj of Natural History. 



of Lake Michigan ; while at Havana nine forms were found. 

 These are as follows : 



Arcella vulgaris Ehrbg. Difflugia globulosa Duj. 



Arcella vulgaris tliscoides Difflugia pyriformis Perty. 



Leidy. Dit'Hugia lobostoma Leidy. 



Arcella vulgaris angulosa Difflugia corona Wallich. 



Leidy. Difflugia aculeata Ehrbg. 

 Arcella dentata Ehrbg. 



These forms appeared in the surface collections frequently, 

 being at times quite a constant factor in the catches. 



CLASSIFICxVTION. 



Many different classifications of the Protozoa have been 

 proposed, but the arrangement given by Biitschli ('80-'89) 

 has been followed throughout in the construction of this 

 list. Kent's " Manual of the Infusoria" ('80-82) was mainly 

 used in the determination of the species of that class. For 

 the species described since the publication of Kent's Manual 

 and Leidy's Ehizopods ('79) citations are given, by date, to 

 the works containing the original descriptions, and these titles 

 may be found in the list of literature appended to this paper. 



SYNOPSIS OF THE HIGHEE GROUPS OF PROTOZOA.* 



I. Class S<(rco(lina. Forms that move about by a simple 

 protoplasmic movement, by a flowing motion, or by the 

 formation of protoplasmic processes (pseudopodia). • 

 1. ^nhclnss llhizoj)oila. Form usually protean ; pseudo- 

 podia lobose or slender, more or less temporary struct- 

 ures without axial support, often restricted by a shell 

 to a part of the body surface. 

 Order Rhizopoda. (Includes all the recent forms of this 

 subclass.) 

 1. Suborder Anuelxea. Naked; pseudopodia lobose 

 or filiform. Two families ; one mostly marine. 

 Am(vhid(e. Pseudopodia usually lobose, never form- 

 ing a network. 



*Compili'<l from Biitschli CSO-'SO). 



