ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 249 



however, not with extreme accuracy, yet sufficiently accurately to 

 show quite a latitude in this respect. Taking a pretty sure gathering, 

 made at the time of the year somewhat remote from the time of the 

 conjugation, I am quite prepared to admit that a preparation of the 

 so-called Frustulia saxonica, for example, will not show any appre- 

 ciable difference in the striation of the frustules ; but I would be 

 quite unwilling to admit that this diatom could not be obtained from 

 another locality considerably more finely or more coarsely marked ; 

 indeed, Count Castracane himself admits a difference, though he says 

 it has never, to his knowledge, exceeded ^, which, as Mr. Kitton shows, 

 gives a range in N. crassinervis, if he understands aright, of 27 to 

 35 in -001 inch! 



" The general character of the striation, parallel, radiate, &c., the 

 character of the median line, if present, the comparative fineness or 

 coarseness of the striae — all these are, no doubt, important, as is also, 

 within limited range, the number of strige in • 001 of an inch. Any one 

 looking over Mr. Habirshaw's ' Catalogue of the Diatomacese ' will 

 realize what a frightful increase of species was made by Ehrenberg 

 and the earlier observers, from considering the number of rays in 

 the genus Adinocyclus as of specific value ; equally pernicious is the 

 custom too largely indulged in at the present day by many hard- 

 working Continental observers, who, looking from the standpoint 

 which Count Castracane appears to advocate, find at stated intervals 

 new species, founded upon little else than finer or coarser striation, 

 or perhaps somewhat different outline. It is, no doubt, quite a com- 

 fortable way of working, and of keeping one's name before the public, 

 when one finds what is supposed to be a new diatom, if only knowing 

 enough to distinguish the genus, one measures, more or less correctly, 

 the length, breadth, or diameter, and the number of striae in • 001 of 

 an inch, giving sometimes a representation, which if it be one of the 

 smaller Naviculce, may too often equally well represent many other 

 forms, and, finally, to coin some unpronounceable word, or immortalize 

 some friend, and send forth the bantling ; since nobody can venture 

 to question its legitimacy, for does it not differ somewhat from every 

 form hitherto figured or described in outline ? And has it not a few 

 more or less strise in • 001 of an inch ? I shall be sorry if, in what I 

 have said, I am considered as censuring men who are unquestionably 

 hard-working and conscientious students of these interesting little 

 organisms. I am only regretting that, instead of labouring to reduce 

 the genera and species of the Diatomacese, and seeking for broader 

 and firmer principles to guide in their study and classification, so 

 many worthy persons are contented to accept trivial distinctions as of 

 generic and specific value, and they are so encumbering the subject, 

 that some day it will be crushed by its own dead weight, giving place 

 to a new structure, utilizing as far as possible the ruins, but erected 

 upon a more solid foundation." 



Schmidt's Atlas of the Diatomaceae.* — The recently published 

 parts of this work treat of the following genera: — Coscinodiscus, 



* A. Schmidt, ' Atlas der Diatomaceenkunde,' Heft 17 u. 18 (8 pis.) Aschers- 

 leben, 1881. 



