NOTES AND MEMORANDA. 101 



Cosmarium in question agrees with the zygospore of the 

 otherwise very different X.anthidium armatum. Cosmarium 

 auriculatum (Reinsch) seems to be, in part at all events, 

 equal to C. perforatum (Lundell). 



A new genus, under the name of Schizospora, is founded 

 by the author for two forms, which, however, were previously 

 described and named by Lundell — Cylindrocystis diplospora 

 (Lundell) and Penium didymocarpum (Lundell). Viewed 

 apart from the zygospore, and having regard only to the 

 arrangement of contents of the parent-cells, these two forms 

 seem generically distinct, but they have in common, no 

 doubt, the double (or twin) zygospore, upon which circum- 

 stance the new genus is founded by Reinsch. But the far 

 more common form, Cylindrocystis Brebissonii, it would 

 appear, sometimes produces double zygospores (see ' Quart. 

 Journ. Micr. Science,' n. s., vol. xiv, p. 423), though single zy- 

 gospores are characteristic, and frequently enough met with 

 in that species. Again, that well-marked species, Closterium 

 lineatum, produces double zygospores, like those of the two 

 species referred to Schizopora by Reinsch, very closely ap- 

 posed, so much so as to become mostly mutually flattened by 

 the pressure, but also, like them, readily separable when 

 mature. Again, Spirotania condensata has double zygo- 

 spores ; but during formation they stand somewhat apart, not 

 closely apposed. The conjugation, in such cases, seems to 

 be effected by the union of the half of the contents of one 

 of the parent- cells with that of the corresponding half of the 

 opposite cell; that is to say (supposing the parent- cells to 

 stand in a vertical position), the contents of the two upper 

 halves passing across to become mutually combined, the con- 

 tents of the two lower halves simultaneously and mutually 

 doing quite the same thing. If, as we think, this is really 

 the process, the resulting spores are truly twin or double 

 spores, not a single spore subsequently subdivided. Seeing, 

 then, that at least four forms appertaining to the diverse and 

 well-recognised genera, Closterium, Spirotsenia, Cylindro- 

 cystis, and Penium, produce these double spores, it would 

 seem as if the proposed genus Schizospora were untenable, 

 or, at least, unnecessary. 



The form recorded as Euastrum gemmatum (Breb.) forma, 

 appears a very well-marked one, and should seemingly rank 

 as autonomous. Onichonema lave (Nordst.), * Symb. Fl. 

 Bras.,' found by that author in a collection from Brazil, is 

 an interesting addition by Dr. Reinsch to the European list. 

 This is an allusion to a few only of numerous very pretty 

 forms described. 



