244 CONTRIBUTIONS FROM TIIK NATIONAL IIKRBARIUZM. 



PijxhUcuUi Elux-nl). in pari; lU-r. Ak;ul. WLs.s. Boil. 1844: 201. \Mb (ef. Mikmg. pi. 



f 



Didtjo pyxis YAn-^inh. in part; ]5cr. Akiul. Wisa. Berl. 1844: 262. 1845. 



/ 



/ 



Creswdlia Grov.; Greg. Tratis. Koy. Soc. Edinl). 

 Grev. Quart. Joiirn. Micr. Sri. 7: IW. 1859, 



Of Lliu original gi'iiu^ Pyxiiliriila Klircfib. Tif> clear \i\vi\ vwn hv (obtained, as Grovillo 

 points ouL,^ Klm'Tilicrg't? diagnosis'' l)oing oqually applicahlr (f>nnyof a hnlf dozen 

 gononi and his figures ))eing l^oyond nuieh question :^oli(ary fru.^tules and Aalves of 

 Gallionella Fdirenl).,^ tluit is, of ^telnsira (\ Ag. Indeed, ho says in his diagnosis of 

 Pyxidieula, '* ^Gallionella divisione spontanea p(u-fecta auf nulla/' The indefinilo 

 Pyxidicula was (hen divided into several genera and subgenera,^ namely, Dietyo- 

 pyxis to aceonuuodate Llie forms with smooth cellular valves and Rtepbanopyxis for 

 those with spinose cellular valves. The former was loosely formed and ineludcMl evi- 

 dent examph's of other g(Mi(n'a, especially >r(>losira and Coscinodisous, and, as the spin(\s 

 of Stephanopyxis are often obscure, perhaps even wanting, on single valves, niembeis 

 of Stephanopyxis would also fall into Dictyopyxis. Sti'phanopyxis includes in its 

 diagnosis and hgures the first consistent concept of these diatoms, and as eluborati^l 

 by Grunow it is the genus to be i)ref<^rred* Unfortunately, however, it was not pub- 

 lished as a g(>mis until 1846,^ KSystiq^bania w^as published as a genus in 1845, and is 

 truly idi^nticalj ils first figures cited above Ixung unmislakabh* (examples of Stei)lian- 

 opyxis; but Syslcphania has never l)een taken up by the diatomists and until all 

 diatomaceous genera liave been tyjjifitHl lliere is no knowing but tluit there may Ix^ an 

 older nam(\ Tlu* above is, therefor(% retained until it can be considered more crit- 

 ically. The diatom of Donkin's Sijslephania cnglica f is excluded. As Grunow 

 pttiniri out. the present genus is vt^ry variabh> as l>etween species, different intliAi(hial3 

 of one species, and even the two valves of one individual, it l>eing not unusual f-^r one 

 valve to Ix' deep(T than the other, to sh.iw greater developnuMit of spines, etc. The 

 confounding of specimens of tlie spurious genus Xanthio])yxis Elu'enb., with this 

 genus has further complicated tlu^ subject, 



Stephanopyxis uppendicula Ehrenb. Mikrog. pL IS. f, .;. 1854, Pritch. Hist, 

 lufus. ed. 4. S2fi. ISG!. Schmidt. Atlas pi IM. f. 18-26, '29, Sl-S2,S4-35. I8SS. 

 Wolle, Dial. X. A. pi 62./, J2 I.',. 1890. 



ryTidta(hi apprndioda Ehreuh, Iter. Akad. Wiss. PorL 1844: 85, :>G4. 1845. Kiitz. 



Sp. Alg. 22. 1849, Weisse, Alel. 15ioL Acad. Sci. St. Petersb. 2: 241, pi 1. f. 17. 

 1855. 



PyxidkuJa hdlnu'm Ehrenb. P>er. Akad. Wiss. Berl. 1844: 85. 1845. 



Pyridtadi apicjilataEhrQiih. Per, Akad. Wiss. Berl. 1844: 85. 1845. Kiitz. Sp, 



Alg. 22. 1819. Weisse, Mel. Piol. A<'ad. Sci. St. Petersb. 2: 241. pi l.f. 16. 1855. 

 SUphanopyxh upiculala Ehrenb. Mikrog. p/. 1[k J\ lib. 1854. Pritch. Hist. Infus. 



ed. 4. 82a. 18(J1. Do Toni, Syll. Alg. 2: il:^7. 1894. Grun. Denkschr, Akad. 



Wieu 48': 8(k 1884. WoUe, Diat. N. A. pi ^:?./ 16. 1890. 

 Didyopy.ns hdhnic.a Ehrenb. Mikrog. pi 19. f. ISa. 1854. 



CresivelUa fnni's Arnott; Greg. Trans. Roy. Soc. Edinb. 21: 5:58. pi 14.f. 109, 1857. 

 SU'phanopyris turn's Palfs in Pritcli. Hist. Infus. ed. 4. 82G. pi o.f. 74. 18G1. Grun. 



Denkschr. Akad. Wien 48^: 87. pi f,J. 7-16 (/. 1S--2I doubtful; not /. 22. 23, 



25). 1881. DeToni, Syll. Alg. 2: 1138. 1S94. Van Hear. Sym^p. pi SSier.f, 12. 



K_ 



^'TrauF. Poy. Soc. Ediidu 21: 537. 1857. 

 ^Ehrenb, Infus. 105. pi 10. f. la-f. 1838. 

 <^Ci. Gallionella op. cit. pi 10. f. 2-7. 



'^Per. Akad. Wiss. Perl. 1844: 262-2(Vb 272. 1845. 



^Op. cit. 1845: 80. 184G. 



/Quart. Journ. Micr. Sci. n. s. 1: 12. pi l,f, Jj. 18G1. 



