298 CONTRIBUTIONS FEOM TITE NATIONAL HEUBAIUUM. 



BIDDULPHIA S. F, Gray, 



Biddulphia S. V. Gray, Nat. Arr. 1: 294. 1821. Van Hour. Synop. 20:i. 1885. 

 Odonldla Q>, Kg. Consp. Crit. Diat. 5G. 1832. Kutz. Bacill. 137. pL IS. f. VIII. 1^4, 



6-8. 1844. 

 Zygoceros Ehrenl>. Tliys. Abh. Akad. Wa^, 15erl. 1839: 131, IGO. pi 4. /. 11-12. 1841; 



Mikro-. pi 35. A. XXIII. J\ 17. 1854. Bail. Am. Journ. Sci. 46: 138. 1844. 

 AmpMtetras Ehronb. in part; Pliys. Abli. Akad. Wiss. Burl, 1839: 122, 142. 1841. 



Kiitz. Tk^cill. 135. pi 19. f. 3. 1844. 

 Cerafauhts Ehreni). in part; Ralfs in rritcli. Hist. Infus. od. 4. 847. 186L (4eve, 



Journ.Qiu4v, MicT.Clubll. 2: J71. 1885, Pant. Beitr. Bacill. Ung. 2: 97.1889; 3: 



pi 29. f. 421. 1893. ' 

 Triceratium Ehroub. Pliys. Abh. Akad. Wise. Berk 1839: 129, 159. pi 4- / 10. 



1841, in part. Rup(T, Quart. Journ. Micr. Sci. 2: 283. /. 1. 1854. Bright. 4: 274. 



pi 17, f. 9-12. 1856. 

 DenticelJa Ehronl).; Ehrenb. in Ber. Akad. Wies. Berl. 1840: 207. 1841. Grun. 



Bonkscbr. Akad. Wien48-: 59. 1884. 

 Odontotropis Gruu.; in part, De Toni, Syll. Alg. 2: 881. 1894. 



In including tho above genera, wholly or In part, in Biddulphia a generic unity is 

 attained that is most desiral)le. This fact has long been appreciated by most diato- 

 mists, and tho synonymy here enumerated is essentially that of Grunow, Van Hourck, 

 Brun, Witt, Boyer, etc. A careful study of these forms convinces me that the plan 

 adopted in De Toni's Sylloge Algaruni of reestablishing Odontclla, Zygoceros, Benti- 

 cella, and Curalaulusas independent genera is unwise. No setof distinguishing charac- 

 teristics important and c:onstant enough to serve as generic definitions can be found for 

 these names. Although this will beconui suniciently evident in considering the s(»pa- 

 rate species following, an illustration or two may be here mentioned. For example, a 

 comparison of OdonUUfi ohlitsa Ktitz./' wilh liidduJphia rnperiana Grev.,^ and of those 

 two wdth Cerataitlur^yalapagcnsis Schmidt, t' will make it clear how futih^ it is to attempt 

 to make gen(Tir dislinctitms between these three diatoms. The genus Zyg{^coros is 

 deservedly obsolete; compare Z. radtaius Bail.^^ with Biddulphia halacna (Ehrenb.) 

 Bright.^ Amphitetras might be bh^nded with that unscientific complex *' Tricera- 

 tium," a genus made up chiefly of evidiait forms of Biddulphia, but in its general 

 structure, in the juarkings a" d processes of the valves, and in the zigzag, chain-like 

 growth of its mniilK^rti it is so typital a lUddidphia thai the example of Van Ilenrc^k, 

 Boyer, and ulhcrs, in < lassing most of its spe<_:ies a^ Biddul])hia certainly deserves 

 imilation. Tlie geims Triceratium is chic^fly made up of biddid])hoid forms, which 

 are here class<Hl in this genus. A full discussinnof the i(4ati()nship between Biddul- 

 phia and Triceratium will be given under the genus Trigonium. See also remarks 

 under the genera Aulacodiscns and Porpeia. 



Biddulphia alaskiensis Mann, sp. no v. Plate XL VI, fkjuue 1. 



Valv<j broadly oval, nearly circular, c^venly and strongly convex, the two proc- 

 esses bar(4y elevated above the surface of the valve; markings of minute and purely 

 radial beading, tluM'e being, however, a slight curvature of the lines toward the si(b's 

 of the two processes; a few minute spines scattered irregularly over the surface of 



a Kiitz. Bacill. pi 18. VIII. f. 1-3. 1844; or Van Hour. Synop. pi lOO, / 11-14, 



ISSl. 



/ 



^Van Heur. Synop. pi 99. J. 4-6. 1881. Trans. Micr. Soc. Lend. n. s. 7: pi 8 

 ll^lS. 1859. 



c Schmidt, Atlas pi 115. f. 8. 18S3. 



f^Smithson. Contr. Knowl. 7: pi l.f. 29. 1854. 



€ Quart. Journ. Micr. Sci. 7: j)l O.f. 15. 1859; or Van H(nu\ Synop. pi 112./, 1. 1887, 



