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YyOn some North American Dcsmidiese. 

 By W. ^^m¥,F.L.S., and G. S. W«st, Assoc. Hoy. CoU. Science. 



(Plates XIl.-XVIII.) 



^ Read 20th June, ISlif). 



While working up a numlier of g-atlierings of Desmids from the United States 

 during the past few years, many new species and varieties have been observed, and our 

 notes thereon have accumulated to such an extent that we considered it would be of 

 interest to publish a few critical remarks, together with descriptions and figures of new 

 forms. 



Material was obtained from the late Rev. F. Wolle, Prof. Aubert of Maine State 

 College, and others. The material supplied by the former was from various parts of the 

 States, but we do not know the particular localities, and consequently cannot give tlu'm 

 after the species. This material was exceedingly rich ; out of one tube alone something 

 like 320 species of Desmids were obtained, but in this case the richness was due to the 

 fact that the contents of the tube consisted of the sediment from a number of other tubes 

 from various parts of the United States. All Prof. Aubert's material was from Maine. 



The descriptions given by Wolle in his ' Desmids of the United States ' are in some 

 cases very meagre, and the figures are often very inaccurate, so much so, that at times 

 it is only with difficulty that one can be sure of the form he had under ol)servation when 

 he made his drawing. We have consequently given amended descriptions as well as 

 accurate figures of some of his species that we have fouad whicii were not accurately 

 described and fissured bv him. 



We also wish to point out that in WoUe's ' Freshwater Alga) of the United States,' 

 p. 42, pi. 62. figs. 7, 8, he records " Staurastrimi cosmarlokles, Reinsch." This is an 

 error; it should be Staurastrimi JPseudocosmariiwi, Reinsch (Contril). Alg. et Fung, 

 t. 9. fig. 1), and must not be confounded with St. costnarioides, Nordst. (in Vidensk, 

 Meddel. 1869 (1870) p. 223 t. 4. fig. 43). 



Many species which are rare or very rare in Europe are quite abundant in the United 

 States ; these also are often the more remarkable species, especially those of the genus 

 Staurastrum. Many species also attain larger dimensions there than in Europe ; there 

 are, however, cases where the reverse obtains : for instance, a few of the smaller species 

 of Staurastrum. Other species are of a more or less unique character, none approaching 

 them in form having as yet been observed from any other part of the world ; such 

 species are St. Wolleanum, Butler, St. minnesotense, Wolle, St. xiphidfophorum, Wolle, 

 St. genujiexum, n. sp., Cosmarium Etoiseamm, Wolle, and C. dentatum, Wolle *. 



* Since the above was written a paper has appeared by Prof. Schmidle in 'Hedwigia,' xxxiv. (1895), entitled 

 "Einige Algen aus Sumatra," in which he describes and figures (p. 304, t. 4. f. 7) a new Co,marium-C.Ashe>imiii; 

 this species, which we have also recently observed in abundance from Singapore, is a close ally of C. dentatum, Wolle. 

 SECOND SERIES. — BOTANY, VOL. V. - ^ 



