114 



THE AMEEICAN MONTHLY 



[June, 



The identification of species of 

 the diatoms is peculiarly difficult on 

 account of their vast number, and 

 from the fact that the original 

 descriptions are scattered among 

 more than two hundred publica- 

 tions. Only two attempts have 

 been made to collect these together 

 in one publication. As a result of 

 those efforts we have, first, Prit- 

 chard's Inftisoria, edited by Ralfs, 

 1860, which contains descriptions 

 of all species and figures of typical 

 species known to him at that time. 

 Large additions have since been 

 made, both to genera and species ; 

 second, the Catalogue of the 

 DiatomacecB.) by Frederick Habir- 

 shaw, privately printed, a work of 

 vast labor and research. This con- 

 tains all the specific names and 

 synonyms known to him at the 

 time, 1879, and references to the 

 authorities, but no descriptions, so 

 that the work is no help for iden- 

 tification for any individual Navi- 

 cula, except by reference to the au- 

 thority of each one named in the' 

 list. There are over six thousand 

 names, and of these eight hundred 

 and sixty-two are recorded as N'a- 

 vicula. Probably one hundred and 

 fifty of these are synonyms, and if 

 every one could be tested by au- 

 thentic specimens, the number 

 might be reduced to three hundred. 

 The others having no legitimate 

 claim to specific names. A little 

 less numerous than the Naviculas 

 are the forms belonging to the 



fenus Coscinodiscus. The magni- 

 cent Atlas of Schmidt, now in 

 course of publication, has figures 

 of about two hundred species of 

 this genus, and does not include all 

 on Habirshaw's list. Your corres- 

 pondent may now learn what it is 

 to identify any one diatom. 



The difficulties of identification 

 may arise from imperfect descrip- 

 tion, or from the use of different 



terms by the authors. One case of this 

 kind may serve as an illustration 

 of the difficulty of describing forms. 

 Harvey and Bailey published in 

 the proceedings of the Philadelphia 

 Academy, 1853, ( Wilkes' Explor- 

 ing Expedition), Hyalosira puncta- 

 ta, with a careful description ; Wm. 

 Smith's British DiatomaceoB, 1856, 

 Vol. II, p. 35, contains Rhab- 

 donema mtrificum, with description 

 — a figure of this was published in 

 the Quarterly Journal of Micro- 

 scopical Science, Yol. YII. II and 

 B's figure was published in 1860 

 — only one hundred copies were 

 printed by the government. A com- 

 parison of the two figures showed 

 at once that they were the same 

 thing. Both descriptions were good 

 and accurate ; yet Bailey's must 

 have been known to Smith, and 

 both were known to Ralfs, for 

 he prints one on page 804 and the 

 other on page 805. The terms used 

 by the two authoi-s in describing 

 the same thing were so different 

 that neither Smith, Ralfs, or anv 

 one else, could recognize it until 

 the figures were compared. This 

 reminds me of an observation of 

 one of the best diatomists in this 

 country, " Figures are nothing, des- 

 cription is all." He was mistaken. 

 I challenge any observer to so 

 describe Biddulphia pulchella, so 

 that any person who has not seen 

 one, or a figure of one, could form 

 any definite idea of its shape, or 

 that any draughtsman could make 

 a drawing that any diatomist could 

 recognize. 



Another difficulty in identifica- 

 tion is that one may find and name 

 a form new to himself, which had 

 been named by another, perhaps 

 years before ; but the first publica- 

 tion was in some inaccessible "perio- 

 dical that the second discoverer never 

 saw, and so both names get into the 

 literature. 



