HOW TO KNOW THE FRESH-WATER ALGAE 



160b Spines long and slender, gradually tapering in the basal part for 

 a short distance, and then abruptly narrowed to a needle. Fig. 



117 



ACANTHOSPHAERA 



Fig. 117 ^2 . Acanthosphaera Zachariasi Lemm. 



This plant can be distinguished from Echi- 

 nosphaerella (Fig. 117) because the spines are 

 long and somewhat needle-like, arising from 

 a base which is decidedly thicker than in 

 the outer section. 



Figure 117% 



161a (159) Cells round. See Fig. 84 GOLENKINIA 



161b Cells oval or ellipsoid 162 



162a Spines at the poles or at the equator of the cell. Fig. 118 



LAGERHEIM1A (CHODATELLA) 



Fig. 118. a, Lctgerheimia longiseta (Lemm.) 

 Printz; b, L. quadriseta (Lemm.) G. M. 

 Smith. 



Unlike Franceia (Fig. 73) cells of this 

 genus have long, needle-like spines con- 

 fined to the poles or to the poles and the 

 equator. There are 3 or 4 species reported 

 from this country which are differentiated 

 on the basis of cell shape and arrange- 

 ment of spines. All are fairly common 

 Figure 118 in the euplankton. 



162b Spines distributed over the cell wall. See Fig. 73 FRANCEIA 



79 



