68 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



bending knee-like towards each other, grow together; zygo- 

 spores elliptical. 



SUB-FAMILY II. MESOCARPE^E. 



The plants of this sub- family are often narrower than those 

 of Zygnemese, with thin cell walls. The chloroplast is a thin 

 axile plate, and all those of a filament usually lie in one 

 plane. The chloroplasts change their position according to 

 the degree of light, turning the edge to bright light and the 

 face to dim light. Reproduction as in Zygnemese. 



Key to Genera. 



Plants reproducing by conjugation Mougeotia* 



Reproduction by non-sexual methods only . .Gonat one 'ma 



Description of Genera. 



Mougeotia A. Br. ( Staurospermum Kiitz. ; Mesocarpus 

 Hass. ; Craterospermum Braun ; Plagiospermum Cleve). 

 Cells long, cylindrical, with axile chloroplasts. Conjugation 

 scalariform ; zygospores spherical or quadrate and more or 

 less flattened with rounded angles. 



M. sp. ( ?), Fig. 85. The method of conjugating is shown 

 in Fig. 280. 



[M. robusta (De Bary) Wittr. ; M. genuftexa (Dillw.) 

 Ag.] 



Gonatonema Wittr. Cells similar to Mougeotia, but re- 

 production only by means of non-sexual spores. Spores pro- 

 duced without conjugation, formed by division of the mother- 

 cells, which are afterwards often burst and bent angularly 

 and alternately at the point of fructification. 



CLASS V. CHARACEiE. 



Algse with a peculiar odor; often encrusted with lime. 

 Thallus a stem with nodes and internodes. The plants grow 

 from a few inches to over a foot in height by means of an 

 apical cell. Whorls of leaves, on which may be borne antheridia 

 and oogonia, grow at the nodes. 



Zoospores are wanting. The organs of reproduction are 

 conspicuous in color and form. The antheridia are spherical, 



