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



Resting spores with thick walls are produced, usually one 

 in each cell, and also two- to four-ciliate zoogonidia. 



M. Wittrockii (Wille) Lag., Fig. 216. 



M. Stagnorum (Kutz.) Lag., Fig. 92. 



[M. abbreviates (Rab.) Lag.; M. amcena (Kutz.) Rab. ; 

 M. crassior (Hansg.) Haz.] 



FAMILY V. HERPOSTEIRACE.E. 



The thallus is a creeping filament, sometimes branched, 

 and growing on larger Algae or other water plants ; most of the 

 cells have a bristle on the back, which is bulbous at the base and 

 separated from the cell by a septum. 



In the sexual reproduction, cells in the centre of the thallus, 

 devoid of bristles, form the oogonia. One oosphere is formed 

 in each oogonium, and is ejected through an opening in the 

 wall. The oosphere is large and slowly motile, provided with 

 four cilia. Smaller cells on the end of the thallus, frequently 

 colorless, form the antheridia. One or two swiftly moving 

 antherozoids, pear-shaped, each with four cilia and two pul- 

 sating vacuoles, are produced in each antheridium, and they 

 unite, outside the oogonium, with the oosphere. 



Herposteiron Nag. (Aphanochaste A. Br., Berth., 

 Huber). Coextensive with the family. 



H. Confervicola Nag., Fig. 80b. 



[H. vermiculoides Wolle.] 



FAMILY VI. CH^TOSPH^RIDIACE^E. 



Thallus creeping, composed of flask-shaped cells more or 

 less loosely joined, and each bearing a very long and slender 

 seta, sheathed at the base. Cell division horizontal, the lower 

 daughter-cell migrating to the side. 



Asexual reproduction by zoospores, formed to the number 

 of four or more (?) in a cell. 



Chaetosphaeridium Klebahn. Coextensive . with the 

 family. 



FAMILY VII. COLEOCH^ETACE^E. 



Small, bright green water-plants. The thallus forms small 

 green cushions or discs. The cells in the common species often 



