294 CONTRTBUTTONS FROM THE NATIO^WL IIERBARTUM. 



Trigonium plano-concavum (Brim) ^TaiiiK 



Triceratluni plano-concavum Bruii \\\ T^ruii & Temp. Mem. Sov*. Pliys. vi Hist. Nat. 



Gcnt^va 30^: <;:]. pi 6. f. .9. 1881K Brun, Lo Diutomipto 1: 5. pi L f. L 1890. 



DeToni, Syll. A1-. 2: 929. 1894. 



Do Toni notes tlie resemhlaiice uf tills wpi'cioM to T. inclajans Grev./* T. nlcobaricum 



Grun.,'> and T. juncalense Grxin.f^ The .similarity exists l)ut ia slighu t'si)eeially ii 



examined with high magnification and sliglitly ol)li<iiie liglit, by which means the 



remarlvahle i)itting of the l)eadw brought nut in the i]iw. pliotograpli in he Diatoini.ste is 



made i)lain. 



Found at ^^tations :i(;S8H, 4029H, Galapagos Islands and Okliotsk Sea. 



Trigonium rusticum Mann, sp. nov. Plate LI, FUiLKK 4. 



Valve triangular, slightly eonvex; ihe angles extended into flat arms witli slightly 

 broadened ends; sitles between the arms inflated; Jnarkings coarse, (Mtnsisting of a few 

 large seattered oval heads at the centerof the valve, thence outward strict ly radiating, 

 decreasing in size to the margin, whicli is very narrow and most minutely })oaded; a 

 minute spine at the apex of each arm. 



Width ))ctween Lhe apices, O.OG mm. 



It resembles remotely T, Viiaocephahmi Grov.*^ and 7\ aahcapiialum Grev.<^ but 

 difft^rs materially in its coarse, strongly radiating beading and especially in its flat arms 

 destitute of the globose elevated ends found in the foregoing. 



Type in the U. S. National Museum, No. 590134, from station 102911, Bering Sea, June 

 27, 1900; 913 fathoms, bottom of gray sand and clay* 



Trigonium sculptum (Shadb.) Mann, 



TriccraUum reticulum Bright, Quart. Jonrn. Micr. Sci. 1; 251. pi 4,f. 17. 1853 (?), 

 not Ehnmb. 



Trivemlimn sculptimi Shadb. Trans. Teller. Soc. Lend. n. s. 4: 15. pi I. J. 4. 1854. 



Moeb. DiaT.-taf. pJ, S, /• 4^ 1890. Schmidt, Atlas pi 76, f, 9-12, 31. 1877, pi 



150, J. 17. 1890. Van Ileur. Synop. pi 109. f. 7-8, pi llUf. S. 1881. Pritch. 



Hist, Infus. ed. 4. 850. 18G1. Wolle, Diat. N. A. pi 106. f. 3-5, pi 111./. 4, 



1890. Petit, Fonds de la Mer 3: 195. 1877. 

 Tnveratiuvi punclatam Bright. Quart.. Journ. Micr. Sci. 4: 275. pi 17, f. IS. 1850. 



Pritch. Hist. Infus. ed. 4, 856. pi 6. /. m. 18(d. De Toni, Sylh Alg. 2: 944. 



1894. Ih L Smith, Sp. Diat. Tyj). no. 002. 1874. Th^ve, Bih. Sv. Vet. Akad. 

 . TIandh 5«: IG. 1878. Van Ileur. Synop. j}l 10!),/, 6\ 9-10. 1881. WoUe, Diat. 



N. A. pi 101./. :>, /:>. 1890. Schmidt, Atla.s pi 7(1./. 19-20, 1SS2; pi SI./. 6-7. 



1885; pi 99,/, .>. 1880. Cleve in N(.rdensk. Vega Kxped. 3: 503. 1883. Petit, 



Fonds de la Mer 3: 194. 1877. 

 Biddulphia sculpla Van Hour. Synop. 208. 1885. 

 Tricitatiu in pardus Svhni'idty Atlas j^Z. 75'./. 1.5. !8S2. 

 Biddulphia reiiculu III Boyer, Proc, Acad. Phila. 1900: 724. 1901. 



This species varies greatly. It is common to find \n the Pa<anc (h-edgings forms 

 with a small curved spine in the center and an evid(>nt but delicate circular ridge, 

 centrally placed, having a radius nf onedialf the distance from centiT to sid(i of the 

 valve. Schmidt./ mentions the spine, saying there are one to three in forms from 

 Nottingham, Maryland; but he does not nuMition the ridges Shadlxtll gives emphasis 

 to three minute rings n<^ar the center. These, like the ridge and sj)in('s nn^ntioned, are 



o Trans. Micr. Soc. Pond. n. s. 14: 8. pi 2./, 21, ISGO. 



& Schmidt, Atlas pi 76./ 22, 1877. 



^'Schmidt, Atlas ;>/. 76./. 13. 1S77. 



^ Trans. Micr. Soc. IiOn(h n. s. 9: 74. pi 9./. 4^ hStd. 



^ Quart. Journ. Micr. Sci. n. s. 3: 231. pJ. Uf./. 20. 1803. 



/Schmidt, Atlas p/. 76./ 26. 1882. 



