THE AMERICAN 



MONTHLY 



MICROSCOPICAL JOURNAL. 



Vol. XII. 



MAY, 1891. 



Ko. 5. 



.1/1 LOinmunicationsfor this Journal, whether relating to business or to editorial 

 matters, and all books, pamphlets, exchanges, etc., should be addressed to Ameri- 

 can Monthly Microscopical Journal, Washington, D. C. 



European subscriptions may be sent directly to the above address accompanied 

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 Triibner (S~= Co., j/ Ludgate Hill, London, or to Mr. W". P. Collins, 757 Great 

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Diatoms : Their Life History and their Classification. 



By Rev. FRED'K B. CARTER, 



MONTCLAIK, N. J. 



[With Frontispiece.] 

 ( Continued from page 8j.) 



We come now to the last point, how to tell to ivliat gerijis a given 

 diatom belongs^ and my answer is, by not attempting too much at 

 once, but attacking the classification in sections. Diatoms, like des- 

 mids, are unicellular algai. But unlike the desmids, they are salt-water 

 as well as fresh-water plants. No desmids are found in salt water. 

 Nearly as many genera of diatoms are found in salt water as in fresh. 

 Others are both fresh-water and marine, and still others are only found 

 fossil. Let us suppose, therefore, that a person wishes to know the 

 forms he meets with in his gatherings from the ponds and ditches. In 

 that case the fossil and the exclusively marine forms may be disregarded 

 by him. Now, this simplifies the matter very much. For example, in 

 the micrographic (which, for the same reason as was given in regard to 

 the Rhizopods, we follow in preference to any later system of classifi- 

 cation) there are over 100 genera of diatoms enumerated, or about five 



List of Fi(;urhs in thk Frontispiece. 



I'lii. 1. Tctracyclus laciistris. 



2. Tabellaria flocculosa. 



3. Terpsinoe inu&ica. 



4. Pleurosigma angiilatum. 



5. Stauroneis phiunecenteron. 



6. Acnanthes siibsessilis. 



7. Navicula (Pinnularia) nobilis. 



8. Anipliora robusta. 



9. Gomphonema acuminatum, var. laticcps. 



10. Cocconeis scutellum. 



11. CymbcUa gastroids. 

 13. Navicula cuspidata. 



13. Mcridion circulare. 



14. Epithemia turgida. 



15. Eunotia robusta, var. diadcma. 



Fig. 16. Eunotia (Himantidium) pecturalis, var. 

 elongata. 



17. Diatoma vulgare. 



18. Asterionella formosa, var. jiracillinia. 



19. Uenticula lauta. 



20. Odontidium hyemale. 



21. Fragilaria capucina. 



22. Melosira nummuloides. 



23. Cyclotella operciilata. 

 34. Stephanodiscus Niat;ara. 



25. Campylodiicus costatus. 



26. Cymatople\ira solea. 



27. Surirella splendida. 



28. Nitzschia laiiceolata. 



29. Amphipleura pellucida. 



Copyright, 1891, by C. W. Smiley. 



