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MANN DIATOMS OF THE ALBATROSS VOYACER. 301 



Biddulphia dubia (Bright.) Cleve, in XorJeiisk. Vega Exped. 3: 508. 1883. Boyer, 

 Troc. Aoul. rhila. 1900: 707. 1901. 

 Odontidium pimctatum Ropor ?, Quart. Juiirn. :Micr, Sci. 7: 180. pJ- 9. f. 9. 1S59. 



Moeb. Diat.-taf. pi. 23, f, 9, 1890. « 

 Triccratium bullostim \Vitt, Journ. Mus. Godof. 1: (i7. pL ^^.Z -^^ 1873. 

 Triceratium dnhium Bright. Trans. Mifr. Sor. I.ond. n. s. 7: 180. pL 9./. /:?. 1859. 



Schmidt, Atlas pi. 18. f. ^G-SO. 1882. 

 Triceratiinn (or Biddulphia) hicorne Hcv^s lUh. Sv.Vct. Akad. Uamll. 5^: 17. pl5. 



/. 5f?. 1878. 

 AmpUletras bicornis Do Toni, Syll. Alg. 2: 902. 1894. 



Though this species has sonu'tiines a ralluT cloye reseml)lance to minute spocimens of 

 B. reticulata Bopor, and this led nie for a time to mako it a variety of tlic latter, a careful 

 examination of many spocimens of both forms, alninchmtly supplied in s{mie of the 

 dredgings, shows them to be essentially distinct. B. dubia is always small, its reticula- 

 tions irregular and of unequal size, their dividing walls thick and crinkled, tlu^ border 

 massive, and the valve outline rhomluc. In B. reiiculaia, on the other hand, a larger 

 diatom, the reticulations are quite regular, generally lu^xagonal, with thin divi<nng 

 walls showing ''knots^^' at their points of juncture, the border is not sonmssive, and the 

 valve outline is either elliptical or w^ith convex sides approaching that figure. Both 

 species have secondary dotted markings within the reticulations, Init those of B. rdicu- 

 lala are smaller and more distinct. The gcn(Tal similarity of these two species has, I 

 think, led to the naming of Schmidt's figures f> ''B. rrficulala Bopcr, var.?" wluTcas 

 tlu^y are certainly closer to B. dubia. The union of Triceratium bicorne Cleve, and 

 Triceratium buUosum Witt, whi(b is recognized l)y D(^ Toni^ and by Boyer.f^ is rather 

 dillicult to admit, in vi(vv of Witt's carefully drawn figure and his plain description. 

 Yet the close similarity of Witt's form to Tfiverafium dubium Bright, is undeniable, as 

 is also the specific identitv^ <.f T. dnbium and T. bicorne. In fact, we have h(Te an 

 illustration of how- misty and indcfinald;- uur specific l)oundaries really are, and how 

 subsequently discovered spcnnmens may bridge over the wide gap that separates 

 apparently quite unlike species. Thissamc condition has been previously referred to 

 under Auliseus punctatus and A, prninnsus Bail. 



Found at station 2885, off Oregtm. 



Biddulphia edwardsii K(^biger; II. L. Smith, Sp. Diat. Typ. no. f>23. 1874. Boyer, 



Proc. Acad. Bhila. 1900: 701. 1001. 

 Odontella edwardsii Grun.; Van Heur. Synop. pi 100. f. 9-10. 1881 . Grun. Denkschr. 



Akad. Wien 48^: 57. pi. 2j, 20. ISSl. De Toni. Syll. Alg. 2: 805. 189.1. 

 Biddulphia obtum Ralfs, (Tr. det. in Van Heur. Synop. pL 100. J. 11-14- 1881. 

 Biddulphia pohjcanthos Brun. Mem. Soc. Bhys. et Hist. Nat. Geneva 31^: 12. pL 12. 



f. 8a-b. 1891, 

 OdontcUa ? polycanfhos De Toni, Syll. Alg. 2: 8(15. 1894. 



I find two w<'ll-marked varieties of the. above polymorphic diatom. Onf^ corresponds 

 closely to what Ibnin floe, cit.) ha? called 7i. pohjcanthos, and that, too, in the forms 

 both with and without the large spines. Brun then fore erroneously makes these 

 spinesamarkof si>ecificdislinctionft)rhisform. Nor can iluMlifferent-eof -B. edicardsii, 

 having diagonal and B. ;^o?//mnf/io5 vertical lines of beading on the girdle, be admitted. 

 For in most gallu>rings of B. edwardsii, where there is considerabh^ diversity in size, 

 both patterns of marking can 1>e seen in abundance. Such, for example, is the case in 

 the II. L. Smith typc-slid(^ no. 623 in poss<^ssion of the U. S. National Museum. This 



« Vi. De Toni, Syll. Alg. 2: Gil. 1892. 



i' Schmidt, Atlas pi 78./. 21 2-L 



cDe Toni, SylL Alg. 2: 973. 1894. 

 d Proc. Acad, Bhila. 1900: 707. 1001. 



