222 CMorophycece 



Pyrenoids are commonly absent, but one or two may occur in 

 some forms. Multiplication takes place by means of autospores 

 formed by the division of the contents of the mother-cell ; they 

 generally arise by oblique divisions, but may be produced by 

 repeated transverse or longitudinal divisions. 



There has never been any doubt concerning the identity of 

 Ankistrodesmus Corda and Rhaphidium Klitz., but this fact 

 only seems to have been acted upon by Ralfs in his ' British 

 Desmids' and Archer 1 when he described his Ankistrodesmus 

 acutissimus. I am indebted to Dr Nordstedt of Lund for 

 furnishing me with full information concerning Ankistrodesmus 

 from Corda's scarce memoir 2 . The remarks made by Corda 

 under the heading of " Ankistrodesmus novum genus," and 

 the description and figures he gives of A. fusiformis, are quite 

 sufficient to establish this genus, and also to show that Klitzing's 

 later genus Rhaphidium is identical with it. Kuntze 3 endeavoured 

 to prove that these two genera should be placed as synonyms of 

 ' Micrasterias Corda (1835) 4 ,' a genus which he tried to establish 

 on the assumption that Micrasterias Ag. (1827) should be 

 relegated to Helierella Bory (1826). Nordstedt 5 has clearly 

 shown that the name ' Helierella ' cannot be used as a generic 

 name, and in consequence Micrasterias Ag. (1827) is a valid genus. 

 It follows from this that Ankistrodesmus Corda is the earliest 

 generic name given to the common plants which Klitzing named 

 Rkaphidium, and as Corda's description and figures are also suffi- 

 ciently characteristic, his name must be accepted for the genus. 



The genus Schroderia was established by Lemmermann in 

 order to include an Alga which had previously been found by 

 Schroder 7 and described by him as " Reinscltiella? setigera." This 

 Alga I have observed from North Yorkshire along with other 

 plankton forms. The only distinction that can be drawn between 

 tichroderia and Ankistrodesmus is the greater attenuation of the 



1 Archer in Quart. Journ. Micr. Sci., n. s. vol. 2, 1862, pp. 255 261, t. xii 

 (in part). 



' 2 Corda in Ahnanach de Carlsbad par J. de Carro, Prague, 1838, pp. 196 198. 

 :i Kuntze Kevis. Gen. Plant, n, 1891, pp. !)04, 905. 



4 Corda in Almanack de Carlsbad, 1835, p. 206. Corda's only mention of 

 Micrtixtvrids falcnta is in the description of the plates on p. 206; there is no text 

 reference and the figures are on t. ii, f. 2i). 



5 Nordstedt in Hedwigia, 1893, Heft 3, pp. 149151. 

 B Leuimermann in Hedwigia, 1898, Bd xxxvii,,p. 311. 



7 Schroder, 'Ueber das Plankton der Oder,' Berichte Deutsch. Bot. Gesellsch. 

 1897, Bd xv. 



