3o6 



Amcriaxii Quarterly Microscopical Journal. 



circular, cask-shaped, 

 with ring-Hke furrows, 

 without furrows, with two teeth on the 

 ends, 

 without gelatin, 

 barrel shaped, 

 3 (seldom 4) cornered, 

 single, or slightly united in families, 

 elliptic, flat, compressed, 



deeply constricted in the middle, 

 borders lipped, 

 zygospores spiny, 

 zygospores warty, 

 borders not lipped, 

 without spines, 

 with spines, 

 not flat, compressed, 

 spherical, spinous, 

 3-5 cornered, corners prolonged, 

 spindle shaped or cylindrical, 

 without median constriction, 

 chlorophyll in the central part, 

 stellate, 



cells generally sickle shaped, 

 cells straight, rounded on the ends, 

 in spiral bands, 

 with median constriction, 



rounded or truncated at the ends, 

 emarginate at the ends, 

 oblong, round Chlorophyll in a longitudinal 

 band. 



HyalotJieca, Ehr. 



Didymopriuui, Klz. 



Bawbusiua, Kt/,. 

 Desniidium, Ag. 



Micrasterias, Ag. 

 Eiiastriwi, Ehr. 



Cosmariuin, Corda. 

 Anthrodesnius, Ehr. 



Xanthidium, Ehr. 

 Sfaiirastruvi, Meyen. 



Clostcriuni, Ntsch. 



Peniian, Breb. 



Spirotcenia, Breb.. 



Plcurotcvnia, Ng. 

 Tciuicmorus, Rfs. 



Pahiiflghva, Ktz. 



The first six of the above are not common ; most of the others 

 are abundant, especially species of Cosmarium and Closteriuiii. 



1. (len. Gonatozygo/i aspen/ium, Rb. short filaments of 0.0 1 d. ; 



rare. 



2. (ien. Geiiicularia spirolienia,d.B. Chlorophyll in spiral bands. 



3. (ien. Sphcerozosma, Corda. Cells elliptic, flat, deeply con- 



stricted in the middle (similarly to C^.vwrt-;-//////'), in ribbon-like 

 filaments. 



Sp. vcrtcbratuni, Rlfs. Cells 0.033 <J-> ^^^t quite so long ; in 

 gelatin. 



4. (ien. Hvalof/icca, Ehr. Cells cylindrical, with rim, united into 



round filaments, with thick gelatinous envelope. 



