STAURASTRUM. 63 



The chief characters seem to be the depressed semicells, 

 separated by a fairly open sinus, and the spines considerably 

 longer at the angles. Liitkemiiller's end view differs con- 

 siderably from that of de Brebisson in its very much more 

 concave lateral margins and more acute angles. 



Lundell criticises Cleve's figure of the zygospore of this species 

 (described by Cleve under the name of St. pihsum), since he 

 found that instead of having appendages first trifurcate and 

 then bifid as figured by Cleve, the zygospores have spines which 

 are 3 or 4 times dichotomous at the apex. Lundell also states 

 that the lower undivided part of the process is a little shorter 

 than figured by Cleve. 



Yar. brevispinum West. (PL CXXXVII, fig. 6.) 



.S7. Brebissonii var. brevispinum West, Alsr. Engl. Lake Di.str. 1892, p. in, 

 t. 9, f . 20. 



Differs from the type in its relatively shorter and 

 stouter spines, and also in the relatively greater length 

 of the cells. 



Length 49 pi ; breadth, not including the spines, 42 5 (JL ; 

 with spines, 45 y. ; breadth of isthmus 17 '5 a. 



ENGLAND.- -Brother's Water, Westmoreland ! 



Geogr. Distribution.- -United States. 



87. Staurastrum pilosum (Xag.) Arch. 

 (PL CXXXVIII, figs. 1-3.) 



Phycasfrum (Amblyactinium) pilosum Nag. Gatt. einz. Ate. 1S49, p. 126, 

 t. 8, A, f. 4, 



Staurastrum pilosum Arch, in Pritch. Inf. 1861, p. 739 ; Rabenh. Flor. 

 Europ. Alg. 1868, p. 212 ; Wittr. Skandinav. Desin. 1869, p. 17, t. 1, 

 f. 8; Xordst. Desm. Arctoae, 1875, p. 34 ; Gay, Monosr. loc. Conj. 1884, 

 p. 68 ; Cooke, Brit. Desm. 1887, p. 150, t, 52", f . 5 : De Toni, Syll. Alg. 

 1889, p. 1166; Anderss. Sverig. Chlor. 1890, p. 12: West, Alg. W. 

 Ireland, 1892, p. 175 ; Alg. aq. dulc. Lusitan. 1892, p. 1503 ; Roy & Biss. 

 Scott. Desm. 1893, p. 23 ; West & G. S. West, Alg. S. England, 1897, 

 p. 494; Borg. Freshw. Alg. Faeroes, 1901, p. 230; West & G. S. West, 

 Alg. N. Ireland, 1902, p. 48 ; Alga-fl. Yorks. 1902, p. 99. 



St. saxonicum f. tenue Schmidt, Gruncll. Algenfl. Liineburg. Heide, 1903, 

 p. 19, t, 2, f. 14. 



Cells small, about as long as broad, deeply constricted, 

 sinus acute, opening widely; semicells subelliptical or 

 subfusiform, angles somewhat acutely rounded, cell- wall 

 covered with delicate spines arranged in concentric 



