280 CONTRIBUTIONS FBOM Mil. NATIONAL HERBARIUM. 



Tripodiscus laxua Mann, -p. nov. I'i \n LIV, noi i 



Valve circular; barely concave to the bases of the processes, thence rapidl) convex 

 Id til.- border; processes five, auriculate, placed one-sixth of a radius from the border, 

 their bases surrounded by <-\ idem hyaline areas; central area circular, slightly r 



>-tenthof a radius in diameter; beading all of one sise; thai is, not decreasing toward 



the border; the rows radial and straight except at the bases of the processes, where one 

 r<>w on each Bide ia curved aboul the base; both primary and secondary row- set wide 

 ;ip;irt with large interspaces, at least the width of two beads, generally of four I 

 giving a loose and open appearance to the valve; border narrow, closely Bel with 

 delicate beads. 



Diameter of valve, 0.076 mm. ; beads 15 in 0.1 nun. 



Type in the 1 .8. National Museum, No 590133, from station 4029H, Bering Sea, June 

 27, 1900; 913 fathoms, bottom of gray Band and clay. 



The nearest approach to the above is the unnamed figure of Schmidt's, which may 

 be a variety of this species. Both bear Borne resemblance t<> .1. kilkellyanu* Grev.,* 

 In: i the processes, the border, and the radially decreasing beading of < ireville's diatom 

 clearly distinguish it from this. 



Tripodiscus marg-aritaceus (Ralfs) Maim. 



Aulacoditcus margaritaceus Ralfs in Pritch. Bist. [nfus. ed. I. Ml. 1861. Schmidt, 



Atlas pi . L876; pi 92. / 12. L886; pi 104./.6 8,pl 106./. t .'. .. L886. 



Ratt. Journ. Roy. Micr. Soc. 8 1 : 35] 353. pi 6./ 8. L888. De Toni, Syll. Alg. 2: 



1 L01. 1894. 

 Aulacodiscu8 crux Ehrenb. Mikrog. pl.S5 A. X VI. f. :. 1854, in part. Grun. Denk- 



Bchr. Akad. Wien 48': 69. L884. Schmidt, Atlas pi 88. f. i .'. L876; pi. ■ 



/. . L886. 

 Aulacodiscu8 molleri Grun.; Schmidt, Atlas pi. 88. f. 14, pi 85. f. 6, pi. 87. / 3, 



pi ./../'. 12. L876; pi 102. f. 1 '.. 18. ! 

 Aylacoducus debyi Pant. Beitr. Bacill. Ung. 1:58. pi :■>./. ?26. 1886. 

 Aulacodiscu8 n. sp.? Schmidt, Atlas pi 87. /. l 8. L876. 



Rattray 6 has named many varieties of this species. The one he calls variety 

 elongata Schmidt thinks should be a separate specie.-. (See last Bynonym above.) 

 Rattray's view is to be preferred. 



Found al Btation 2823, Gulf of California. 



Tripodiscus oregonus (llarv. A: Bail.) Mann. 

 Aulacodiscus oregonus Barv. & Bail. Proc. Acad. Phila. 6:430. 1854. Pritch. Hist. 

 [nfus. ed. I. 845. pi. 6./. >. 1861. (.rev. Quart. Journ. Micr. Sci. 7: 156. pi. 



r. :. L859. Moeb. Diat.-taf. pi 11. /'. /. 1890. Schmidt, Atlas pi 84./ 

 L876; r l. 107. /.6 :. L886. Ratt. Journ. Roy. Micr. Soc. 8 1 : 358. 18 8. DeToni, 

 Syll. Alg. 2: L109. L894. 

 Aulacodiscu8 oregoru nsis Bail.<& Barv. in Wilkes U. S. Explor. Exped. 17: 17:;. 1874. 

 Found at station 2835, off Lower California. 



Tripodiscus orientalis (Grev.) Maim. 



Aulacodiscus orientalis Grev. Trans. Micr. Soc. Lond. n. b. 12: 12. />/. .'./. 6. 1864. 

 Schmidt, Atlas pl.84./. t 8. L876. Grun. in Fenzl, Reise No vara Bot. 1: 103. 

 L870. Ratt. Journ. Roy. Micr. Soc. 8': 361. L888. De Toni. Syll. Alg. 2: 1111. 

 1894. 

 Found al Btation 3688, Paumotu Islands. 



"Solimi.il. Vtlas pi 105./. 8. ' 



is. Micr. Soc. Loud. n. b. 11: 70. pi [./ /.. 1863. 



