242 CONTIUBUTTONS FROM THE NATTOXAT- IfEREAKlUM. 



uf each valve; Lli*.- uiaLiilicuri genorully (not always) aoparuted from i\\v nv^t ol the 

 valve by an inv^Milar liiir or suture; nizc of the uiul>ilicuri varying from a meri' ispeck 

 (larrly wanting) to tw(Hthirdri the diameter of the valve; valves tilighily convex to 

 h<nnispherieal; markings^ outside of the umbilicus, of delicate beading arranged 

 in close straight or curved linos crossing (^ach (»tlier (»bli(pu4y to th(^ radii; ra<lial 

 lines, continuous or diyconliiuiou.s, sometimes pro(^o(Mling from the und>ilicus toward 

 or to the border, in the latter ca^e dividing tlic valve into unequal si^gnu^nts; border 

 narrow, hyaline; cuiuun'ling /ajuc narrow, liyaline* 



Podosira argus (Irun. in S<ltrHuder, lieiLr. K(^nnl. Kauk. 132. 1878; Jour. R<ty. Micr, 

 Soc. 2: (J91. /)/. ;>/./. 6. 1879. De Toni, Syll. Alg. 2: 1:^(14. 1894. 

 Podosira rariryatn Sclnnidt, Atlas pL IjO.f. A tL 1889. Wolle, Diat. N. A. p/. 69. ■ 



/ ,^.1890. 

 Podoaira pavifira ('ha.si^ in Walk, tfe Chase, Noti^s on Diatoms 1: 5. yl. 1.J. 5. 188G. 



This oxquisilcly beautiful <liatom is a wide di*parture from the tyi)e of this genus. 

 The umbilicus is reduced tt) an indefinite scar, which is sometimes wanting. The 

 valve is divid'Hl into three definite areas, like tliose of restodisciis, but without 

 processes. It agrees in these particulars with 1lu^ (Hjually aberrant Podosira {Pyx- 

 idicida) radiata O'Meara.'^ Both lliese stand so much alone that they almost merit 

 separation from this genus. It will, however-, be observed that three authors inde- 

 pendeully assigned it to the present genus. There is also a close enough likeness 

 to Podosira corolla Schmidl,^ to give support to tliis ideniihcation. 



The species is fairly abuiulant at station 2920II. I am quite sure that in all the 

 specimens examintnl the massive bosses ornainenting the central area are not, as 

 Schmidt claims, tliickenings on both sides of fh(^ valve, but are on th<^ inider (con- 

 cave) side only. The outer of the three bands is also different, b(Mng not hyaline 

 but plainly crossed wdth two sets of lines, diagonal (45^) to the radii, as is common in 

 this genus; within this is the band of fine radiating lines, as depicted by Schmidt. 



Found at stations 2920II and 300811, ("'alifornia to Hawaiian Islands. 



Podosira stelliger (I^ail.) Mann. 



Hyalodhcus stelliger Hail. Smithson. Contr. Knowh 7: 10. 1854. Van Ileur. 

 Synop. 21:5. j)l. Slf, /, 2. 1881; Treat, Diat. 448./. 17H, pi 22. f. (150. I89(i. De 

 Toni, Syll. Alg. 2: VMM. 1894. Pritch. Hist. Infus. ed. 4. 8M. l8(iL Grun. in 

 Fenzl, lleise Novara Bot. 1: 27. 1870. (deve, \Vi\\, Sv, Vet. Akad. Ilandl. 1'=': 



4. 1873. 

 Craspedodiscus? sLella Khrenb. Mikrog. pL 35B. IW f. 11. 1854; lier. Akad. Wiss. 



Berl. 1854: 238. 1855; Pritch. Hist. Infus. ed. 4. 939. 1861. 

 Podosira maculala W. Smith, Synop, Brit. Diat. 2:b4.pL49-f, 32S, 1S5G, Pritch. 



Hist. Infus. ed. 4. 815. 18C1. Schmidt, Atlas pi. 139. f. 7 if. 4? unnamed). 1889, 

 J fyalodiac as stelliger li'dil,; Fricke's Verzeich. 1902. H_. L. Smith, Sp. Diat, Typ, 



no. 420. 1874. Schmidt, Jahresb. Konim, Deut. Meere 2: pL S.f. 2S. 1874. 



Wolle, Diat. N. A. ph 69./. 4-5. 1890 (figures poor). 

 IfyalodiRCus wacidatfi.H (devOj T^ih. Sv. Vet. Akad. Handl. 1^"^: 4. 1873, 

 Melosira ntaculafd hag(*rs. Bib. Sv. Vet. Akad. Ilandl. 3^'': 9. pi. /,/. 7. 1870. 



The peculiar radiating lines of this species, dividing the disk, outside of the umbil- 

 icus into what Bailey calls "sectorial groups'^ and its relatively coarse beading define 

 this species well. It, of course, grades somewhat Into other species, being like all 

 nuMubers of tins genus variable. Its umbilicus is generally small. The fleve & 

 Mollcr type no. 1 bearing this name is v(Ty wi<le of the mark. It has practically no 

 umbilicus but rather a ring, small 'And obscui'e, with radial interrupted daslu'p, like 

 an Actinocyclus; in fact it differs from AclinonjduH interpunctatuii (Bright.) Ralfs 



^/ Journ. Tann. Soc. Bot. 15: 58. ph /./ 9, 187(1. 

 ^SchmidL, Atlas yjL 140, f. II, 12. 1889. 



