128 BRITISH DESMIDIACE^. 



IRELAND. --Derryclare Lough, and lakes E. of Lough 

 Bonn, Co. Gal way ! 



Geogr. Distribution. Austria. Bornholm. Scan- 

 dinavia. Siberia. 



Figures of this variety have never been published, but Witt- 

 rock, in describing it, says that it is very similar to t. 22, f. 9 g, 

 in Kalfs, 'Brit. Desm.' and t. 8 B, f. n, o, p in 'Nag. Gatt. einz. 

 Alg.' 1849. Its distinguishing feature seems to be that the 

 processes are longer. It may be that this variety is merely a 

 form of St. cremdatum. 



Var. simplex W. & G. S. West. (PL CXLIII, fig. 5.) 



St. polymorplmm var. simplex West & G. S. West, Freshw. Alg. Orkneys 

 & Shetlands, 1905, p. 26, f. 28. 



Cells relatively longer than in the type, not including 

 the processes ; processes very slightly divergent, with 

 one circle of denticulations, and the apex of each tipped 

 with 4 minute spines ; cell- wall otherwise quite smooth. 

 Vertical view quadrangular. 



Length, without processes, 21-23 JJL ; breadth, without 

 processes, 12*5-15 \L ; with processes, 23-28'5 \L ; breadth 

 of isthmus 7*6 \L. 



SCOTLAND. Near Lerwick, Shetlands ! 



Var. munitum West. (PI. CXLIII, fig. 6.) 



>S7. polymorphum var. munitum West, Alg. Engl. Lake Distr. 1892, p. 20, 

 f. 35 ; Schmidle, Lappmark Siisswasseralgen, 1898, p. 60 (forma). 



Processes provided with 3 or 4 series of sharp denticu- 

 lations ; cells in vertical view triangular, sides straight. 



Length 31 (JL ; breadth, with processes, 36 ^ ; breadth 

 of isthmus 8 {ju 



ENGLAND. Esthwaite Water, Lancashire ! 



Geogr. Distribution. Sweden (form). 



131. Staurastrum affine W. & G. S. West. 

 (PL CXLII, fig. 23.) 



,S7. affine West & G. S. West, Freshw. Alg. Orkneys and Shetlands, 1905, 

 p. 26, t. 2, f. 27. 



