16 Transactions of the Society. 



Spirotaenia condensata Breb. 



,, obscura Ealfs. 

 Closterium lunula Ehrb. 



„ turgidum Ehrb. 



„ acerosum Schrank. 



„ Elirenbergii Menegh. 



„ Dianse Ehrb. 



„ didymotocum Corda var. 13 Ealfs. 



„ cost at um Corda. 



„ striolatum Ehrb. 



„ juncidum Ealfs. 



„ acutum Breb. 



* „ setaceum Ehrb. Bog pools, Eoche and St. Denis, 



occasional. 

 Micrasterias denticulata Breb. 

 ,. rotata Grev. 



,, crenata Breb. 



Euastrum verrucosum Ehrb. 

 „ oblongum Grev. 



* „ oblongum var. integrum n. var. Fig. 18. 



Frond about the size of the normal form, oblong in outline. 

 Each frustule rather longer than broad, broadest at the base, 5-lobed ; 

 basal lobes nearly half the length of the frustule, concave; lateral 

 lobes also concave; terminal lobe quite entire. Along the centre of 

 each frustule is a row of conspicuous protuberances; and there are 

 two other lateral protuberances in each frustule. 



Peat bog, Mawgan. This form appears to be intermediate between 

 E. ohlongum Grev. and E. multilohatum Wood. It differs from the 

 typical E. ohlongum in little but the entire absence of the notch in the 

 terminal lobe, which hardly seems sufficient for the establishment of a 

 new species. WoUe (Desmids of the United States) also mentions the 

 occasional absence of the notch. 



Euastrum crassum Breb. 



* ,, crassum var. coRNUBiENrfE n. var. Fig. 19. 



Frond about the size of the normal form, 140 yu. long by 105 yu. 

 broad at its greatest width. Outline of frustule without the terminal 

 lobe nearly rectangular; sides nearly parallel; lower half somewhat 

 convex, then a rounded projection, and terminating in a jirominent 

 cuneate shoulder. Terminal lobe emarginate, but not deeply notched. 

 Two rows of large protuberances in each frustule, and in addition a 

 protuberance in the lateral projections. 



Bog pool, St. Denis. Closely resembles the very abundant E. 

 crassum, with the exception of the projection below the shoulder. 



Euastrum Didelta Turp. 

 „ ansatum Ehrb. 

 „ circulare Hass. var. a Ealfs. 

 „ pectinatum Breb. Very abundant. 

 „ elegans Breb. ^ inerme Ealfs. 



