81 



Archer describes this species as sub-elliptic in outline, with 

 the sides somewhat barrel-shaped and the ends truncato- 

 rotuiid. He states that the zygospore is twisted in those 

 instances in which the conjugating cells lie at right angles to 

 ciich other. 



7. Penium suboctangulare West. 



(PI. VIII, figs. 14-19.) 



Penium suboctangulare West, Alg. W. Ireland, 1892, p. 128, t. 24, f . 20 ; 

 "West & G-. S. West, Alg. S. England, 1897, p. 479; Nordst. Index 

 Desniid. 1896, p. 246. 



Cells minute, about 1^ times longer than their dia- 

 meter, oblong-ellipsoid, unconstricted, apices broadly 

 rounded ; cell-wall smooth and colourless. 



Zygospore quadrate or oblong, compressed ; angles 

 truncate and retuse ; cell-wall thick, ultimately be- 

 coming brown. 



Length 14-1(5^; breadth 10/ti; length of zygospore 

 25-28 /t, breadth 20-25 /<, thickness 18/. 



ENGLAND. New Forest, Hants, (with zygospores) ! 



IE ELAND. Lower Lake of Killarney, Kerry (with 

 zygospores) ! 



8. Penium minutissimum Nordst. 



(PI. VIII, figs. 20-23.) 



Ptnium minutissimum Nordst. Norges Desm. 1873, p. 43, t. 1, f. 21 ; 

 Cooke, Brit. Desm. 1886, p. 45, t. 17, f . 10 ,- West & G-. S. West, Alg. 

 Maclag. 1895, p. 47 ; Norclst. Index Desniid. 1896, p. 171 ; West & G. S. 

 West, Alga-fl. Yorks. 1900, p. 46. 



Cells minute, 1^-2 times longer than their diameter, 

 unconstricted or very slightly constricted in the middle, 

 subellipsoid, very slightly but gradually attenuated 

 from the middle towards the apices which are broadly 

 rounded ; cell-wall smooth, yellowish. 



Zygospore subquadrate, angles rounded and slightly 

 prominent ; broadly elliptical from both vertical and 

 lateral views ; cell-wall yellowish. 



Length 12-16^; breadth 9-10 /; length of /y go- 

 spore 1C f.i, breadth 14^. 



6 



