29G CONTRIBUTIONS FROM THE NATIONAL HERBARIUM, 



Triccratium grave Schmidt, Atlas pi. 77, f. 17. 1882. Triian & Witt, Dial, Ilayti 22. 



pi 7.f. 1, 13. ]888. Do Toni, Syll. Alg, 2: 94(). 1894. 

 Biddulphia tabcUanum Boycr, Proc. Acad, rinhi. 1900: 718. 1901. 



The form dcscribiHl and rigunnl (with some douLt) as this species by Grove and 

 Sturi is another specic^s, as Schmidt makes it,'n'alhng it T. wajiis Gr. Sc St. It is clearly 

 a Biddidphia, having strongly developed processes at the angles. T. renulosum Grev. 

 iti simply a delicate variety oi T, UibcUariiim, 



Found at stations 2807, 300-1, Galapagos Islands and Ik-ring Sea, 



Trigonium trirdtas (I^run) Mann. 



Trkeratium irinitos r>rnn; Schmidt, Atlas j^/. KULf. S-4. 1891. 



The general l>uild of tins species is that of a A'ery nunute T. arctkinn; l»ut the l)ead- 

 ing is very dil'iV-rtMit, coarse, eaeh head having a C(^n1ral dot, showing no trace of radial 

 arrangement. The beads are similar to those of T. luminosuni Brnn & Tt^mp., espe- 

 cially as figured by SchnudL.'^ But uidike the latter, they have no process(^s at the 

 angles (seen best in the original figure), c The border is unusually massive and iraiis- 

 v(TS(dy striated. My specinn^i agrees best with the variety called viinima {C\g. i 



abov(*). 



Found at station f5G03, Bering Sea. 



Trigonium zonulatuni (Grev/i Mann. 



Tnceraiiiim zonalaiauvCiW'X . Trans. Micr. Sc»c. Loncb n. s. 13: 102. pi, .9./. 17, 1805. 

 Moeb. Dial.-taf. pi. (i9.f. 11. 1890. Schmidt, Atlas pi. 77./. oV-J7- 1882; pi. DJf. 



f. 9. 1886. 

 Am phiieiras zonulalu !)(> Toni, Syll. Alg. 2: 900. lS9b 

 Biddidphia parvula lioyer, Proc. Acad. Phila. 1900: 725. 1901, in pari. 



Tins diminutive and fine(batom is exceedingly abiindani in the single hydrographic 

 sounding bidow. It (mtirely lacks the characteristic Biddulphia (or ''Ampluteras ") 



processes at tho anglos. 1 therefore think it is iuiidmissible to class it as Boyer or De 

 Toni does. Itism^t exactly the same as the Am phifdras parrula Jan, & T?al)h.*^ and it 

 is a question if that name could stand, having l)een published the same year, 1803, 

 as J^. parruZa Grev., a tutally different diatom. De Toni, Cleve, and others class T. 

 zonulatutn and A. parvala sej)arately. 



My specimens ari' ri'nuukably \uiifonn in size, all measuring about 0.02 mm. 



Found at station 4029II, Bering Sea. 



DITYLUM BalL 



Dilylum J5ai]. Best, Journ. Nat. Hist. 7: 332. pi, (L 10-15. 1861. Van Hear. Synop. 

 19G. 1885. De Toni, Syll. Alg. 2: 1017. 1894. Boyer, Broc. Acad. Bhila. 1900: 



730-731. 1901. 

 Tnceratium Ehrenb. in jjart; West, Trans. Micr. Soc. Lond. n. s. 8: IJ9. pL 8.f. 1^ 



5, 8. 18G0. Van Ileur. Synop. pi. 114 J- S-9, 1881. 



The members of this genus have not the nnuotest likem^ssto forms of Triceratium 

 Ehrenb., except in the imperfect triangular outline of tlu- valves, and this is inctm- 

 stant. Tlieir pellucid, sparingly silicilied frustules; their hmg and massivi- central 

 spines; the peculiar topography of the valves, with a flat eentral art^a surrountUnl by 

 portions sloping downward at a considerable angh', and the grc^at breadth of the gir- 



« Schmidt, Atlas ;>?. 127. f. 1. 



^ Schmidt, Atlas pJ. 159. f. 8. 1890. 



cMem. Soc. Pliys. Hist. Nat. Geneva 30'^: ph G,f, S. 1889 



t^Babh. Beitr. 1: 4. pi. l.f. 4- 1SG3. 



