STAURASTRUM. 119 



ytaurastrum paradoxum Ehr. Inf. 1838, p. 143, t. 10, f. 14. 



<S7. tetracerum Ralfs, in Ann. Mag. Xat. Hist. 1845, v. 15, p. 150, t. 10, f. 1 ; 



Brit. Desm. 1848, p. 137, t. 23, f . 7 ; De Bary, Conj. 1858, p. 71 ; Arch. 



in Pritch. Infus. 1861, p. 744 ; Rabenh. Krypt,-fl. Sachs. 1863, p. 191 ; 



Lund. Desm. Suec. 1871, p. 68 ; Xordst, Norges Desm. 1873, p. 35 ; Delp. 



Spec. Desm. subalp. 1877, p. 161. t. 11, f. 25-28; Kirchn. Alg. Schles. 



1878, p. 168 ; Cooke, Brit, Desm. 1887, p. 182, t. 63, f . 5 ; De Torn, Syll. 



Alg. 1889, p. 1232 ; West, Alg. W. Ireland, 1892. p. 187 : Alg. E.igl. Lake 



Distr. 1892, p. 21 ; Roy & Biss. Scott. Desm. 1893, p. 26 ; West & G. S. 



West, Alg. Madag. 1895, p. 80 ; Alg. S. England, 1897. p. 495 : Liitkem. 



Desm. C. China, 1900, p. 124 ; Comere, Desm. de France, 1901, p. 160, 



t. 11, f. 7; West & G. S. West, Alga-fl. Yorks. 1902, p. 104; Freshw. 



Alg. Orkneys & Shetlands, 1905, p. 25 ; Alg. Third Tanganyika Expedit. 



1907, p. 127 ; Kaiser, Alg. Traun. u. Chiem. 1914, p. 153. 

 Phycastrum paradoxum Kiitz. Spec. Alg. 1849, p. 180 (in part). 

 ^t'liirnstrum paradoxum var. tetracerum Rabenh. Flor. Europ. Als. 1868, 



p. 210. 



-S'/. Arachne var. tetracerani Jacobs. Desm. Danemark, 1875. p. 208. 

 St. tetracerum var. unill<itn,n West & (J. S. West, Ale. Madag. 1895, p. 80, 



t. 9, f. 6. 

 vSV.. fjracillimum var. bir(nli>i/iiin Bolilin, Flor. Alcol. d'eau douce d'Acores, 



1901, p. 55, t, l,f. 12. 



Cells minute, about as long as broad, or up to 1 5- times 

 longer than broad, including the processes; constriction 

 fairly deep, sinus open with a minutely excavated apex ; 

 semicells short and rectangular, apex straight or slightly 

 concave, upper angles produced to form long, strongly 

 diverging processes, gradually attenuated towards their 

 apices, and with 4 or 5 undulations ; apex of processes 

 minutely emarginate. Vertical view fusiform with the 

 poles drawn out to form nodulose processes. Cells often 

 twisted at the isthmus. 



Zygospore globose, with about 16 long processes 

 swollen at the base, and once or twice dichotomous at 

 the apex (Lund.). 



Length, without processes, 7-10pi ; with processes, 

 24-28 pi ; breadth, including processes, 18-30 PL ; breadth 

 of isthmus 4-5 pi ; diam. zygosp., without processes, 16 u ; 

 with processes, 30 pi. 



ENGLAND. Cumberland ! Westmoreland ! Lanca- 

 shire ! W., K, and E. Yorks ! Cheshire (Roy). Leicester 

 (Roy). Norfolk ! Warwicks ! Worcester ! Gloucester 

 (Ralfs). Surrey ! Sussex (Ralfs). Kent ! Hants ! (Roy). 

 Wilts ! Devon ! Cornwall ! 



WALES. General (often abundant) ! In the plankton ! 



