22 DAVENPORT ACADEMY OF SCIENCES. 



being observed. Fig. 31 illustrates a spineless variety with pseu- 

 dopodia almost withdrawn. 



ASSULINA Ehrenberg. 



Shell of chitinous material, oval in shape, compressed, usually 

 made up of hexagonal plates. Mouth truncating the oral extrem- 

 ity, elliptical, with uneven edges. Pseudopodia as in Euglypha. 



AssuLiNA SEMiNULUM L,eidy. 



Having the characters of the genus. 



Length, 40 microns. (Fig. 30, PI. V.) 



The shell ranges in color from transparency to dark brown, 

 probably depending upon the age. The hexagonal plates are 

 arranged in alternating rows and about the oral aperture are 

 placed so as to give a notched appearance to the border. 



Pseudopodia are exceedingly delicate and transparent, branched 

 but not anastomosing. 



The species is apparently a rare form in the state, but few 

 specimens having been found. Seldom may one see the organism 

 with its pseudopodia extended. Its habitat is the ooze at the 

 bottom of ponds. 



TRINEMA Dujardin. 



Body enclosed within an elongated, chitinous shell; fundus 

 rounded, oral extremity narrower and obliquely truncate. Mouth 

 circular, sub-terminal, in the center of the truncated border. 

 Pseudopodia very delicate and transparent. 



Trinema enchelys Eeidy. 



Having the characters of the genus. 



Length, 40 microns. (Figs. 33-34, PI. V.) 



Usually the shell of Trinema enchelys presents a homogeneous 

 appearance with a smooth outline, but in some specimens the 

 shells show evidence of being made up of minute oval plates. 



In size the species varies greatly, as also in the density of the 

 material composing the shell. Some are transparent while others 

 are completely opaque. 



Figure 33, Plate V, represents a form of the apparently homo- 

 geneous variety, it being a ventral view. Fig. 34 represents the 

 same form from a lateral point of view. 



