EDMONDSON — PROTOZOA OF IOWA. 1 3 



Figure 9, Plate II, represents a typical form of the spined var- 

 iety, also possessing branched pseudopodia. 



Figure 12, Plate II, is a spineless variety having a deep annu- 

 lation not far from the mouth. It has been found in great abund- 

 ance in Dickinson county and in other localities. 



Figure 8, Plate II, illustrates a very minute variety which is 

 frequently observed in the process of conjugation. 



Dijflugia pyrifonnis is widely distributed, found in fresh water 

 among algas, and usually in an active state. 



During the summer of 1905 many individuals were found hav- 

 ing the protoplasm bright green in color, due probably to previ- 

 ously ingested plant tissue, upon which the species ravenously 

 feeds. The pseudopodia being adhesive are enabled to draw into 

 the mouth such food particles as may cling to them. 



Reproduction takes place, as in the other species of the genus, 

 by the extrusion of a portion of the cell-mass and the formation 

 of a new shell about the extruded portion, after which the two 

 individuals separate. 



DiFFLUGIA GI^OBUIvOSA Duj. 



Shell more or less spheroidal in shape, composed usually of 

 quartz sand. Mouth large, terminal, seldom with a well-marked 

 neck. 



Length, 100 microns. (Figs. 6-7, PI. II.) 



This is one of the smallest and rarest species of the genus. All 

 of the forms observed in this state were of the spheroidal shape 

 represented by Fig. 6, Pi. II, with the mouth truncating the oral 

 extremity. The fundus is usually evenly rounded, bearing no 

 spines. The mouth, as shown by Fig. 7, PI. II, is large, round, 

 and without lobes. 



The habitat of this species is similar to that of the other mem- 

 bers of the genus, but seldom does one observe active individuals. 

 Specimens were taken from Lake Okoboji during the summer of 

 1905, and also from the waters of Johnson county. 



DiFFLUGIA CRATERA Leidy. 



Shell usually of small size with an oval or rounded fundus pro- 

 longed anteriorly into a broad cylindrical neck. Mouth terminal. 



Length, from 55-150 microns. (Figs. 14-15, PI. II.) 



