STAURASTRUM. 103 



and Achill Isle, Galway, Kerry, and Lough Beg, London- 

 derry ! 



Geogr. Distribution. France. Germany. Switzerland. 

 Galicia and Austria. Hungary. Italy. Norway. Sweden. 

 Denmark. Bornholm. Finmark. " Poland. "N. and s! 

 Eussia. Faeroes. Iceland. Greenland. Siberia (var.). 

 Japan. Turkey-in-Asia. Australia. United States. 

 Canada. Guiana. Brazil. Patagonia. 



The nearest relative of St. paradoxum is St. gracile. From 

 the latter species it is distinguished chiefly by its diver- 

 gent processes. Both species are subject to considerable varia- 

 tion, and transitional forms between the two species are not 

 infrequent, in consequence of which specimens are occasionally 

 encountered which cannot with any degree of certainty be 

 referred either to the one species or to the other. Even amongst 

 the collections of Professor West are some gatherings labelled 

 with a query. This proves that the identification of some 

 forms is impossible. 



The divergence of the processes is not usually very great in 

 the typical form, but some specimens from plankton have pro- 

 cesses which are more divergent, and very often relatively 

 longer as well. Other plankton forms bear a superficial 

 resemblance to St. pseudopelagicum. The strength of the granu- 

 lation varies, as does also the length of the apical spines of the 

 processes. Sometimes the granules at the base of the processes 

 become strengthened into short spines, and in some cases there 

 is a row of such spines just within each lateral margin in the 

 end view. The "body" of the semicell is usually quite smooth. 



St. paradoxum is quite a common species in this country, and 

 has a world-wide distribution. The biradiate form has been 

 recorded from the plankton of Bracebridge Pool, Sutton Park, 

 Warwicks. 



Var. longipes Nordst. (PL CXLVI, figs. 2, 3.) 



St. paradoxum var. longipes Nordst. Norges Desm. 1873, p. 35, t. 1, f. 17 ; 

 Cooke, Brit. Desm. 1887, p. 171, t. 59, f . 4 ; De Toni, Syll. Alg. ] 

 p. 1212 ; West, Alg. N. Wales, 1890, p. 18 ; Turn. Freshw. Alg. 

 1893, p. 125, t. 4, f. 4 c and f ; Roy & Biss. Scott. Desm. 1 3, p. - 

 Borge,Schwed. Siisswasserplankton, 1900, p. 6, t. 1, f. 4 ; Liitkem. 1 

 Central China, 1900, p. 124 ; West & G. S. West, Alga-fl Yorks. 1 

 p. 106 ; Him, Desm. Finnland, 1903, p. 22 ; West & G. S. West, Further 

 Contrib. Plankton Scott. Lochs, 1905, p. 504 ; British Freshw. 



