284 ONTBIBUTIONS PBOld THE NATIONAL HERBARIUM. 



Una Cleve, Bih. Sv. Vet. Akad. 1 ': 8. pi. I.J. 7.1873. Van Heur. Treat. I Mai. 

 118./. J DeToni, Syll. Alg. 2: 771.189 i i Rep. Voy. Chall. Bot 



2:89. pi 9./. ?. 1« 



wrdxa Peng. Le Diatomiste 1: l»>7. pi. /. /. / .,. 1892. Van Heur. Treat 

 Di.n. 117./. I - H De Toni, Syll. Alg. 2: 822. L894. 

 Leptocylindriem ? Cleve, Diat. Kattegat. 2. 1889. Perag. Le Diatomiste 1: 104. 



1892. De Toni, Syll. Alg. 2: 822. L891. Eng. & IV. Pflaneennun. I" 1 : 84. - 

 Dactyliosolm Castr. Rep. Voy. Chall. Bot. 2: 75. pi. 9./ :. L886. Perag. Le Dia- 

 tomiste 1: 104. />/. /./. 6 .". 1892. DeToni, Syll. Alg. 2: 821. L891. Eng. A IV. 

 Pflanzenfam. 1": B3. /'. 136. I s "';. 



Ehrenberg's concepti f this genua ires so vague thai, aside from the name, its 



founding ie mainly due to Brightwell; and the name itsel! loses all meaning if we 

 remove from it the forms represented by Cleve's Lauderia. It- members are pelagic, 

 as a class subtropical, and, with the exception of II. L. Smith's /.'. meruit, marine. 

 Their terminal valves, bearing one to many setae, are widely separated by a tubular 

 /.one l.uilt up of either very narrow bands or wedge-shaped pieces imbricated into a 

 tube. The frustules thus constructed arc delicate, elastic, and not densely Bilicified. 

 Yet with this Btrong generic harmony there arc differences of absorbing interest from 

 tin- fad that here more than in any other gen US we find variations that -land as inter- 

 mediate plan structures' between it and several other distincl genera. Tin- peculi- 

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

 genera enumerated above. Their affinities are most strikim:. The form called by 

 Wesl Attheya decora lead.- t<» the genus Chaetoceros; Guinardia, with its rudimentary 

 mucronate scar, i- close to that doubtful example of the genus Biddulphia, which 

 Peragallo calls Cerataulua bergonii] the -}>«■« ic- included in the invalid genus Lau- 

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

 iosolen are very Buggestive of Melosira; while in Perogalloa meridiana Schutl we have 

 a probable Bpecies of Chaetoceros with the zonal view of Rhizosolenia; and finally 

 R. 8tolterforthii Perag. is amazingly like thai delicate but genuine example of the 

 genus Eucampia which Cleve has miscalled Molleria (■<>rn<ita. , > It will help to make 

 evident the impossibility of bounding these newer genera in any way thai will dis- 

 distinguish them generically if we carefully compare specimens of the Bpecies enu- 

 merated, or, in the absence of these, if we contrast in plate I of Peragallo 's Monograph c 

 the following figures: Rhizosolenia murrayana Castr. (f. 20), and /»'. atolterforthii (f. 17) 

 with Guinardia flaccida (Castr.) Perag. (f. 1 1; this latter (as shown in f. \\\, noting the 

 Mnall mucronate scar, with Cerataulus (Cerataulina) bergonii IVrau r . if. Mi; again, 0. 

 fiaccida (f. l> with the lower frustuleof Ijni<I<ri<i delieatula Perag. if. 13). The fact is, 

 if -in— is put solely on the setae and other appendices of the terminal valve- we 

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

 we -hall have Btrikingly distincl hut valid species of Rhizosolenia. with much more 

 in common structurally than the differences that distinguish them. 



Rhizosolenia hebetata Bail. Am. .lourn. Sci. LI. 22: 5. pi. l.f. 18 19. L856. Bright 

 Quart, .lourn. Micr. s<i. 6: 94. />/. 5. f. -',. L858. Pritch. Bist. fnfus. ed. I. B66. 

 1861. Cleve, in Nordensk. Vega Exped. 3: 186. pi. 38. f. 69a-f, L883. II. L. 

 Smith, Sp. Diat. Typ. no. lis. L874. (.run. Denkschr. Akad. Wien 48: 

 pi :,. (. \8 50. L884. DeToni. Syll. Alt:. 2: MM). L894. Perag. Le Diatomiste 

 1: ill. pi 5.f. 10. L892. Moeb. Diat.-taf. pi l ',./. ■',. L890. 

 This may he considered the type diatom of Bering Strait and the adjacent arctic 



waters. Bailey's original specimens came from Kamchatka. Grunow'e also, and 



" Le Diatomiste 1: />l. /../'. 5, t6. L892. 

 6 Van Heur. Treat. Dial. ltd./. 192. L896. 

 - Le Diatomiste 1: />l. i. L892. 



