278 >NTBIBUTIONS FROM rill-: NATIONAL HERBARIUM. 



Bail., and / I mii Schmidt, a somewhat aberrant phase of the genus, 



for in"-i members of » 1 1 « - genua have simple beading for markings, radiall) arranged, 

 with a more or less pronounced hyaline central area from which hyaline Lines run 

 to the bases of the mtermarginal pi Indeed, Bupodiscus of Bhrenb. (not of 



Ratt. came to represent jusl the aberrant phase of T.argut. Bui the differenci 

 neither constant aor striking enough to warrant a separate genus, and Rattray, Schmidt, 

 and others, have done rightly in uniting these with those generally called Aulacodiscus. 

 Rattray has unwisely retained the name Bupodiscus for a group of diatoms having 

 n-'ii,' of the characteristics of Bhrenberg's forms, nor containing a single Bpei 

 named by him, namely, species with from one to four processes that are qoI protuberant 

 horns, but more of the nature of the "ocelli" in the genus Auliscus or of the pseudo- 

 uodule in Actinocyclus. The genus bo framed is of doubtful value, and if it be ueeded, 

 i its members which can not be referred to Auliscus where most of them belong) 

 won 1.1 be better placed under an entirely n«\\ generic titl<\ rather than under the mis- 

 leading name Bupodiscus. Bupodiscus Kan. (not Bhrenb.) is therefore Left < >ui of 

 the above synonymy.^ 



Tripodiscus affinis I Grun. I Mann. 



Aulacodutus affini* Grun. ; Schmidt, Atlas pi. /.•<'/'./. 9-10. L876. Ratt. Jburn. Roy. 



aficr. Soc. 8 1 : 359* De Toni, Syll. Alg. 2: L110. L894, 

 Aulacoditcut chasei Pant. Beitr. Bacill. Ung. 1: 57. pi. 19. f. 

 Auld&odisCUS oregoriUS sparsfau-punctata < irun. ; Schmidt. Atlas pi. 107. f. 5, 3 (figure 



unnamed . L886. 



Rattray includes in this species the unnamed figure of Schmidt's noted in the last 

 Bynonym as well as Grunow's subspecies of .1. oregonus Bail. 1 think this union is 

 justified. Hut there Beems to me more uncertainty about placing here the type and 

 varieties of A. lunyacsehii Pant.6 Bowever, there is a similarity between these and 

 the above, and indeed between all these and A. oregonus BaiL 



Found at Station 3604H, off British Columbia. 



Tripodiscus beringensis Mann. PLATE L, HG1 RE 6. 



Valve circular, Btrongly marked with coarse heads, becoming -mallei- only near the 

 margin; processes nine, submarginal; from the base of each a hyaline rectangular 

 space, two rows of head- wide, extending radially inward for about one-fifth the 

 radius, from thi> point a single row of beads running to the small circular central area. 

 this inclosed by a ring formed of the nine terminal beads of these row.-: the segments 

 ,-n hi ended by these nine radial rows set with heads of equal size in parallel Lines, only 

 tic centra] one in each Begment being, therefore, radial. 



Diameter of valve 0.063 mm. ; beads 64 in 0.1 mm. 



Type in the U. S. National Museum, No. 590130, from Station 4029H, Bering 

 June 27. L900; 913 fathoms, bottom of gray sand and clay. 



Tripodiscus concentricus Mann. sj>. nov. PLATE I. IV. in.i EtEfl 1. 2. 



Valve circular, nearly Hat for one-half the radius, thence moderately and evenly 

 convex to the margin; marking of large head-, of uniform Bize until within one-fifth a 

 radius length of the margin, then of smaller beading, bo placed a- to form a single spiral 

 about the minute hyaline center, thence pa— i mlt into a series of strictly concentric 

 circles and the component beads of each circle s<> arranged as to form with those in the 

 other circles perfectly radial rows, the beads set Blightly closer in the concentric circles 

 than in the radiating rows: at the distance of one-half a radius from the center, where 

 the valve becomes convex to the margin, the two concentric circles of head- a trifle 



"<f. Journ. Roy. Mm.-. Soc. 8 J : 900. L88fl 



M'ant. Beitr. Bacill. Ung, 1: ■>'.•. /</. / ,/'. .'. pi. l.f.9 to, /</. IS.}. 



