284 CONTRIBUTIONS FROM THK NATIONAL HERBARIUM. 



Laud('naV\e\e, liih, Sv. \vi. Akad. l^': 8. pi. l,f. 7. 187;^ Van Heur, Treat. Diat. 

 418./ 136, 18%. DeToJii, SylL Alg. 2: 771. 1892. Castr. Rop. Voy. OhalL Hot. 

 2: 80. p^ ILf, 4, S. 1886, 



Guinardia Terng. Le Diatomi^te 1: 107. pi 1. f. 1-5, 1892. Van Ilciir. Treat, 



Diat. 417./ 135, ISOH. De Toni, Syll. Alg. 2: 822. 1894. 

 Leptocylindricus ('?) Clcve, Diat. Kattegat. 2. 1889. Pcrai?. Le Diatomiste 1: 104. 



1892. De Toni, SylL Alg. 2: S22. 189L En-. & Pr. rflanzenfaln. l^'': 8L ]S9G. 

 Dadyllosolni Castr. Rop. Voy. Chall. Bot, 2: 75. pL 9./. 7. 1S8G. Perag. Le Dia- 



tuiuiste 1: 104. pi. l,f. 6-7. LS92. De Toni, Syll. Alg. 2: 821. 189L Eng. &: Pr. 



PflanztMifarn. 1">: SS./, /,y^. |S%. 



Ehreiiberg\s coiu-optiuu uf this genufi was m vague that, aside from tlie name, its 

 founding i^ mainly due to Briglitwell; aiul the uame itself loses all meaning if ^ve 

 remove from it the forms represented l)y Aleve's Laudoria. Its mond)ers are pelagie, 

 as a class subtropical, and, with the exception of IL L. Smith's 7^ cricnsis, marine. 

 Their terminal valves, l)earing one to many setae, are widely separated by a tubular 

 zone built up of either very narrow l^ands or wedge-shaped pieces imbricated into a 

 tu!)e. The frnstulcs thus constructe<l arc delicate, elastic, and not densely silicified. 

 Yet with this strong generic harmony there are differences of absorbing interest from 

 the fact that here more than \\\ any other genus we find variations that stand as inter- 

 mediate i)lau wtructures between it an<l several other distinct genera. This peculi- 

 arity of Kluzosolenia has given occasion for the creation of various questionable 

 genera enunuTated above. Their atiinities are most striking. Tlie form (^alled by 

 West Atthya decora leads to the genus Chaetoceros; Guinardia, ^\ith its rudimentary 

 mucronate scar, is close to that doul.>tful example of the genus Biddulphia, which 

 Peragallo calls Ccrataidus hcrgonii]^ the species included in the invalid genus liau- 

 deria have valves like Stephanopyxis and girdles like Striatella; those called Dactyl- 

 iosolen are very suggestive of Melosira; while in Perayalloa meridiana Schutt we have 

 a proba1)le species of Chaetoceros with the zonal view of Rhizosolenia; and finally 

 /?. siolU rforthii Perag. is amazingly like ihat <lelicate but genuine example of the 

 genus Eucanipia whicli (Teve has miscalled MoUrria cornufa.^ It will help to make 

 evident the ini2>ossil)ility of Ijounding these newer genera in any way that will dis- 

 distinguish them geuerically if we carefully compare specimens of the species enu- 

 merated, or, in the al)sence of these, if we contrast in jdate 1 of Peragallo's Monograi>h'' 

 the folloAving figure?: Rhizosohma viinrayatia Castr. (f. 20), and 7^ i^iolti rforthii (f. 17) 

 with Cmnardki flaccida (Castr.) Perag. (f. 4); this latter (as shown in f. 3), noting the 

 small mucronate st-ar, with Ceratcudus {Ctrataulina) hrrgomi Perag. (f. 16; again, G. 

 Jlaixida (f, 1) with the lower frustule of Laudcria delicatula Perag. (f. 1.'^). The fact is, 

 if stress is put solely on the setae and other appendices of the terminal virlves we 

 shall have the various genera above enumerated; but if we take the entire frustule 

 we shall have strikingly distinct but valid species of Rhizosolenia, with much more 

 in common structurally than the differences that distinguish them. 



BhizosolerdahebetataPaiL Am. Journ. Sci. IL 22: 5. p?. ;./ 18-10. 185G. Pright 

 Quart. Journ. Micr. Sci. 6: !I4, pi. 5.f, 4^ 1858. Pritch. Hist, Infus. ed. 4. 8(U]. 

 ISGl. Cleve, in Nordensk. Vega Exped. 3: 48G. pLSS. f. 69a f. 1883, H. L. 

 Smith, Sp. Diat. Typ, no. 448. 1S7L Grun. Denkschr. Akad. Wien 48-: lifj. 

 pi. .5./ 48-50. 1SS4. De Toni, SylL Alg. 2: 829. 1894. Pera- Le Diatomiste 

 1: 114. pi 5.f. 10, 1892. Moeb. Diat.-taf. pi 14.f. 4. 1890. 



This may be considered the type diatom of Bering Strait and the adjacent arr-tic 

 waters. Biuley\s original specimens came from Kamchatka, Cirunow's also, and 



"L(^ Diatomiste 1: pi l,f. S, 16. 1892. 

 ^'Van ll(Mir. Treat. Diat. 401./ nij. 1890 



cLe Diatomiste 1: pi 1. 1892. 



