268 CONTRIBUTIONS FROM nil NATIONAL HERBARIUM. 



The matter of this confusion haf been bo extensive!) treated by t !astracane " that n<» 

 attempt to add to what ii i ln-r«- said i- here. The Bubja i will !»•• referred 



to in tin- rrp..n under the genus Trigonium. The present genus \s in some instance! 



bo close i" Eemiptychus Bhrenb. that g 1 definitions are bard to formulate. & 



Nevertheless the utility of the two genera i- considerable, and their approach is not 

 « lose enough i" merge this genu* into that of Ehrenberg. 



Stictodiscus buxyanus Grev. Trans. Micr. 8oc. Lond. n. b. 9: K). pi. ',. f. l :. 1861. 

 Moeb. Diat.-taf. pi. 57./ ; • ls, " , • Schmidt, Atlas pi 131. f 3. L888. Truan 

 & Witt, Diat. Hayti 19. pi. .,./. i .;. --- De Toni, Syll. Alg. 2: 1313. 



1894. 

 lodiscus hUttlingerianus Truan & Win. Diat. Hayti l'.». pi. :,. f. n. 1888. 



It i- a question whether or not 8. johnsonianus Grev. should be placed hen 

 synonym. The chief distinction is the single lines of radiating beads in 8. Johnson- 

 minis and the multiple lines of beading, especially uear the border, in 8. bury- 

 anus. This difference, as seen in Greville'e original figures and in plate 5 of Luard 

 and Win i- hardly adequate to keep these apart. There is even lees excuse for mak- 

 ing a n«'\\ Bpecies of 8. hUttlmgerianus on the trivial ground that the shadow lines at 

 the center of tin- valve do not anastomose. 



Pound at stations 2807, 3784, < ralapagos [slands, and north of Aleutian Islands. 



Stictodiscus gelidus Mann. sp. now Di.vn: L, PIOURl 5. 



Valves circular, almost fiat; marked with very large flat di.-k.-. which, like the 

 interspaces, are smooth and shining; the largest, four to five in number, arranged 

 about the center of the valve in a ring, each disk being one-eighth the diameter of 

 the valve in width <»r fully 0.0] mm. wide, thence decreasing in size to the border of 

 the valve, where they are one-third as large; 12 to L8 radiating bul irregular lines 

 proceeding from the border toward the center, but not reaching it. as is common in 

 tin- genus; at the center one -mailer disk invariably perforated by a vermiform central 

 pore. larL-er aboN «• and narrowing inward to a line point : rim narrow and hyaline. 



Diameter of valve, 0.058 to 0.105 mm. 



Type in the U. S. National Museum, No. 590124, from station 4029H, Bering Sea, 

 June 27, 1900; 913 fathoms, bottom of gray sand and day. 



Stictodiscus johnsonianus Grev. Trans. Micr. Soc. Lond. n. s. 9: II. pi. 



L861. De Toni. Syll. Alg. 2: Kill. L894. Trtian A: Witt. Dial. Hayti 20. j>I. 5. 

 . :>. pi. 6.f. 16. L888. Moeb. Diat.-taf. pl.37.f.S. - 

 Stictodiscus jeremianus Casta*. Rep. Voy. Chall. Bot. 2: no. L886. Truan A Win. 



Diat. Hayti 20. pi. 5. f. 10, { >l. S.f.t. L888. Schmidt. Aila. pllSl./.l. 1888. 



De Toni, Syll. Alg. 2: L320. L884. . 

 Triceratium jeremianum Schmidt. Atlas />!. ;:,./. I la. 1882. 

 Stictodiscus truani Win. in Truan A Witt. Dun. Bayti 1!». pi I L888. 



Schmidt, Atlas pi. 131. f. '.. L888. De Toni, Syll. Alg. 2: L317. L894. 

 Stictodiscus caraibicus Truan & Win. Dial. Hayti 20. pi. 5./. 14. L888. De Toni, 



Syll. Alg. 2: L319. L894. 

 Stictodiscus radiatus Castr. Rep. Voy. (hall. Bot 2: 1 17. j>I. i. f. i. L886. De Toni, 



Syll. Alg. 2: L316. L894; 



In admitting a gpecific difference between this diatom and S. buryanus, chiefly on 



the baeifl of the multiple character of the radial row- of beading in the latter and 



sCastr. Rep. Voy. Chall. Dot. 2: L12 1 L6. I : 



&Cf. Arachnoidiscus barbadensis Schmidt, Atlas /</. 68. f. //. with Stictodiscus hard' 



ma, ,,'ainis <ire\. pi. ,d lhe-e tWO with StictodisCUS QYOVei Schmidt. j>l. /,',\ 



/. 5 :. 



