280 CONTRIHUTIONS FROM THE NATIONAL HERBAKIUM. 



Tripodiscus laxus ]\Iann, pp. nov. Plati<: LIVj ficiURp: 3. 



Valve circular; barely concave to the ba^^es of the procct^ses, thence rapidly convex 

 to the border; procewi^es hve, aurit^uhitc, placed one-Rixthof a radius from the border, 

 their bases surrounded by evident hyaline areas; central area circular, t^iightly rugotse, 

 one-tenth of a radius in diameter; beadinji; all of one size; tliaLis^ notdecreat^in<,Mo\vard 

 the border; the rows radial and straight except at the l>ase8 of the jjrocesyes, where one 

 row on each side is curved about the base; both primary and secondary rows set wide 

 apart wdth large interspaces, at least the w'idth of two beads, generally of four beads, 

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



delicate beads- 



Diameter of valve, 0.07G mm.; beads -J5 in Od mm. 



Type in the IT. S. National Museum, No. 590133, from station 4029II, Bering Sea, June 

 27, 1900; 913 fathoms, buLLom of gray sand and clay. 



The nearest apj^roach to the above is the unnamed fjgur(i of Schmidt's, ^^ whic:h may 

 l>e a variety of this species. Both bear some rc^scmblance to A. kilhilyanus Grev..^> 

 but the processes, the border, and the radially decreasing beading of (JrevilleTs diatom 

 clearly distinguish it from this. 



Tripodiscus margaritaceus (Ralfs) Mann. 



Aulacodiscus margarilaccKS Ralfs in Prilch. Hist. Tnfus. ed. 4. 844. 18GL Sc^hmidt, 



Atlas plS7.f. 4-7. 187G; j)L 92. f. 12. 188G; pi 104, f^ 6~S, pi- 105. f. 1-2,4^ ISSQ, 



Ratt. Journ. Roy. Micr. Soc. 8^: 351-353. pi 6./. :i 1888. Do Toni, SylL Alg. 2: 



1101. 1894. 

 Aulacodiscu.^ crux Ehretd). Mikrog, pi 35 A. XVI. f. 2, 1854, in part. (Irun. Denk- 



schr. Akad, Wien 48-: 69. 1884, Schmidt, Atlas pi 33. / 1-2. 1876; pi 102. 



/. 4^ 188C. 

 Aulacodtscas mdllcri Grun.; Schmidt, Atlas pi 33, f. 14, pi o5,f. 6, pi ^7. J. S, 



pi 4i,f, 12. 187G; pi 102, f, 1-2, 13. 188G. 

 Aulacodlscus dibyi Pant. Beitr. Bai'itl. I'ng, 1: 58. pi 25. f. 220, 18SG. 

 Aulacodiscus n. sp.? Schmidt, Athifi pi 37. f. 1 S. 187G. 



Rattray'^ has named many varieties of this species. The one ho callw variety 

 clorujata Schmidt thinks should he a separate species. (See last synctnym above,) 

 Rattray's view is to be preferred. 



Founil at station 2823, Gulf of (\dif(jrnia. 



Tripodiscus oregonus (Ilarv. & Bail.) Mann. 



Aulacodiscus oregonus Ilarv. & Bail. Proc, Acad. Pliihi. 6: 430. ]854. Pritch. Hist. 

 Tnfus. ed. 4. 845. pi 6. f. 4- 1801. Grev. Quart. Journ. Micr. Sci. 7: 150, pi 



7./. 2. 1859. Moeb. Diat.-taf. pi 21. f. 2. 1890. Schmidt, Atlas pi 34./. 4-6. 



1876; pi 107, f, 6-7, 1886. Ratt. Journ. Roy. Micr. Soc. 8^: 358. 18S8. De Torn, 

 ■ Syll. Alg. 2: 1109. 1894. 

 Aulacodiscus oregoncnsis Bail. & Ilarv. in Wilkes U. S. Kxplor. Expcd* 17; 176. 1874. 

 Found at station 2835, off Lower California. 



■ 



Tripodiscus orieiitalis (Grev.) Mann. 



Aulacodiscus orienialis Grev. Trans. Micr. Soc. Lond. n. s. 12: 12. pi 2,f. 6. 1804. 



Schmidt, Atlas pi 34^/ 1-3. 1876. Grun. in Fenzl, Reise Novara Bot. 1: 103. 



1870. Ratt. Journ. Roy. Micr. Soc. 8^: 361. 1888. De Toni, SylL Alg. 2: 1111. 



1894. 

 Found at station 3688j Paumotu Inlands. 



« Schmidt, Athvs pi 105. J. S. 1886. 



^ Trans. Micr. Soc. Lond. n, s. 11; 70. pi 4-/- 14- 1863 



