No. 10.] FRESH-WATER ALG^. 6l 



C. prelongum (Breb.) Delp., Fig. 157. 



C. lineatum Ehrb., Figs. 157a, 158. 



C. decorum Breb., Fig. 159. 



C. areolatum Wood, Fig. 161. 



C. Diana Ehrb., Fig. 162. 



C. Jenneri Ralfs, Fig. 160. 



C. parvulum Nag., Figs. 163, 164. 



C. moniliferam (Bory) Ehrb., Fig. 165. 



C. Leibleinii Kutz., Fig. 166. 



C. Leibleinii var. curium West, Fig. 167. 



C. rostratum Ehrb., Fig. 168. 



C. rostratum var. breviro stratum West, Fig. 169. 



C. subcostatum Nord., Fig. 170. 



C. Brebissonii Delp., Fig. 171. 



Docidium Breb. Cells straight, cylindrical or fusiform ; 

 ends rounded, truncate or smooth, constricted in the middle ; 

 each semi-cell furnished with a basal inflation. The base is 

 plicate with a granule under each plication. Chlorophyll axile 

 and an axile row of pyrenoids. The ends have a vacuole con- 

 taining dancing granules. 



D. Baculum (Breb.), Figs. 103, 223. 



D. verticillatum (Bailey) Ralfs, found but not figured. 



Pleurotsenium Nag. In shape much like Docidium, 

 without plications at the base of the semi-cells. The ends are 

 truncate and usually furnished with a ring of tooth-like pro- 

 jections. The parietal chloroplasts are longitudinal and are 

 provided with several pyrenoids. The centre of the cells usually 

 contains large vacuoles, and in the apical ones moving granules 

 are often seen. 



P. crenidatum (Ehrb.) Rab., Fig. 224. 



P. Archerii Delp., Fig. 225. 



P. Trabecula (Ehrb.) Nag., Fig. 226. 



P. nodosum (Bail.) Lund., Fig. 283. 



P. sp. (?), Fig. 101. . 



Tetmemorus Ralfs. Cells like Penium, except that the 

 ends are slightly cut and the middle is constricted. One 

 central chloroplast with a single row of pyrenoids is present. 

 Cell wall mostly punctate or granulose. 



