296 ONTBIBUTIONS FROM ill!. NATIONAL BEBBABIUM. 



3< liuii.li. Atlas pi. 77./. f 7. 1882. Truan A Witt, Diat. Hayti 22. 

 L888 De Toni, Byll. Alg. 2: 946. L894. 

 '•■//,//,/.! /,»/.,//«/ i B .• i Pi n \..M. Phila. 1900: 718. L901. 

 The form described and figured with some doubt) as this Bpeciee l>> <d"\«' and 

 Sturt is another species, as Schmidt makes it,° calling il T.ma G &8t [t is clearly 

 a Biddulphia, having strongly developed processes at the angles. T. w nulosun I 

 is simply a delicate variet) of r. tab Uarium. 



Pound al stations 2807, 3604, Galapagos Islands and Bering 



Trigonium trimtas I'.iun Maim. 



m trinitas Brun; Schmidt, Atlas pi. f66./. - ,. 1891. 



The general build of this species is that of a v ery minute T. arcticum; but the bead- 

 ing is \ ery different . coarse, each bead lu»\ ing a central dot, Bhowing n<> trace of radial 

 arrangement. The beads are similar t<> those of T. luminosum Brun iV: Temp., espe- 

 cially as figured by Schmidt.* Bui unlike the Latter, they have no processes al the 

 angles Been besl in the original figure). c The border is unusually massive and trans- 

 versely striated, hiy specimen agrees besl with the variety called minium 

 abo • 



Found at Btation 3603, Bering Sea. 



Trigonium zonulatum Grev. Mann. 



/' ia ratium zonulatum Grev. Trans. Micr. Soc. Lond. n. b. 13: 102. pi. 9./ 17. 

 Moeb. Diat.-taf. pi. 69./. 17. 1890. Schmidt, Atlas pi. 77./. 66 37. L882; pi. 94. 

 /. 9. L886. 



Amphitetras zonulata DeToni, Byll. Alg. 2: 900. L894. 



Biddulphia parvula Boyer, Proc. Acad. Phila. 1900: 725. L901, in part. 



This diminutive and fine diatom is exceedingly abundant in the Bingle hydrographic 

 Bounding below. It entirely Lacks the characteristic Biddulphia or "Amphifc i 

 processes at the angles. I therefore think it is inadmissible to class it as Boyer < D< 

 Toni does. Lt is not exactly the same as the Amphitetras pan ula Jan. A: Rabh.d and it 

 is a question if thai name could Btand, having been published the same year, L863, 

 as l parvula Grev., a totally differenl diatom. De Toni, Cleve, and others cl 

 zonulatum and A. pan ula separately. 



My specimens are remarkably uniform in size, all measuring about 0.02 nun. 



Found at Btation 4029H, Bering Sea. 



DITYLUM Bail. 



Ditylum Bail. Bost. Journ. Nat. Bist. 7: 332. pi. 6. 10-15. L861. Van Beur. Synop. 

 L96. L885. De Toni, Syll. Alg. 2: L017. L894. Boyer, Proc. Acad. Phila. 1900: 

 730 731. L901. 



Ehrenb. in pan. West, Trans. Micr. Soc. Lond. n. s. 8: L49. pi. 8./. 1, 

 I860. Van Eeur. Synop. pi. 114./ ■'• '■>■ L881. 

 The members of this genus have no1 the remotest Likeness to forms of Triceratium 

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

 stant. Their pellucid, sparingly silicified frustules; their Long and massive central 

 spines; the peculiar topography of the valves, with a fiat central area surrounded by 

 portions sloping downward at a considerable angle, and the great breadth of the gir- 



" Schmidt, Atlas pi. //;./. /. 



bSchmidt, Atlas pi. 159./. 8. L890. 



■ tf< in. So< Phys. Bist. Nat. Geneva 30': pi. S.J 3 L889. 



<i Kal.h. Beitr. 1: 1. pi. /../'. .;. L863. 



