264 CONTRTBUTTONS FROM TITE NATIONAL TTEKBAKTUM. 



The name ^ ^ Eiipodisev s ? subtilis'' "Fhronberg « ougliL to be dropped out of considera- 

 tion, as there is no indication of the character of the diatom Lh(i author ha<l in mind. 

 Ralfs's spec ies, however, differs In no respect, except in iLs ])seudonodule, fixnn Cosd- 

 nodiscus suhlilis P'hrenb.^ and especially from the figures in Schmidt's Atlas pL 57- 

 f. 11-lG. 



Found at stations [iOGOII, Kuril Islands, and ,T>S8 II, Sen of Okhotsk. 



Actinocyclus tesselatus (Roper) Ralfs in PriLcdi. Hist. Iiifus. cd. 4. 835. ISGl. 



Eupodisais tesselatus RoptT, Quart . Joiirn. Micr. Sci. 6: If*, pi. J. f. }-}. 1858. 

 Moeb. Diat.-taf. ph JJ,f, i~lh. 1890. 



lioperia tesselata Gvuu,; Van Ileur. Synnp. pi. US. J. G-7. 1881. Halt. Journ, Roy. 



Micr. Soc. 8-': 57. 188S. Do Toni, Syll. Alg. 2: 1087. 180h 



As has been pointed out in tlie discussion of the genus^ tht; sole difference between 

 Actinocyclus and Coscinodiscus is tlu^ presence in the former of the pseudonodule. 

 Altliough this species contrasts strongly will] olliers of tht» gt^nus because of its reticu- 

 lated marking, it does not differ in that resptn't from Coscinodiscus. where such mark- 

 ings arc ihe dominant ones. I see, tlicrefore, no reason to place this in a new genus. 

 The pseudonodule is less dense and convex than in most Actinocycli, though there 

 are exceptions even to tliis; Init 1h(Tf^ can be iKt question tliat it is the homologue of 

 that structure. 



Found at stations 208011, 2000II, l)<4we<ui San Francisco and Hawaii. 



CRASPEDODISCUS Ehrenb. 



CraspcdodiacitsYAnvuh, Ber. Akad. \\'iss. Herl. 1844: 200. 18-15; Mikrog. pi lS,f. 108. 



Tritch. Hist. Infus, ed. 4. 831, 939. 1801. De Toni, Syll. Alg. 3: 1198. 1894 



Griff. & Ilenf. Micr. Diet. ed. 3. 203. pi -jS. f. 21. 1875. Bright. Quart. Journ. 



Micr. Sci. 8: 95. pi, 5.f. 6, pi O.f. 12, Moeb. Diat.-taf. pi 29. f. 12, 1890. 

 Cosdnodiii€}(S^\\\'v\\\), in part; KOtz. Sp. Alg, 120. 1849. 

 Pyridinda Elirenb. Brr. Akad. Wiss. B(t1. 1844: 85. 1845, in part. 

 Porodiscus Grev. in part; Orun.; Sclnnidt, Atlas pi C)i>.f. 0, 1888. 

 Ilyalodiscus Ehrenb. Her. Akad. Wiss* Berl. 1853: 520. 1854, in part; Mikrog. pi 



35A. xxiilf. Ga b. 1854. 



Although tins genus is of questionable validity it is not possible at tliis time to dis- 

 tribute its members amoiig tlie two or three g<^nera wliicli it most nearly resembles. 

 It stands (dosest to Coscinodiscus, as is evid<Mit by such exiimj)Ies of Crasprdodisevs 

 coscinodiscus Ehrenb. as that figured in Sclimidt.^ Ontlieothi^* hand, if hnuls over 

 imperceptibly intoPorodiscusGrev., as in the case of Schmidt's figure/? wliichGrunow 

 calls Crasprdodisrus oblongus^ but whicli Rattray^ looks upon, and rightly, as Poro- 

 discus oblongjfS Grcv. Nor is it surprising that in such cases of ISrightwellia as have a 

 very minute ring of beads separating Ihr central portion from tlie outer band of the 

 valve, this ring should be looked upon as essentially the same as the suture that usually 

 separates these two portions in Craspedodiscus./ It is, liowever, best to hold tliisgejuis 

 distinct; and acconlingly the union of it with Coscinodiscus by KiJIziiigf/ has been 

 generally disregarded. 



a Ehrenb. I5er, Akad. Wiss. Berl. 1855: 302. 185G. 



bPhys. Al)h. Akad. AViss. Hcrl. 1841: 412. ;)/. /. 7/7./. IS. 1813 

 c Schmidt, Atlas pi GG.f. -7. 1881. 



dOp- cit./. 7-9. 



^Proc. Roy. Soc. Edinb. 16: 071. 1889. 



/Cf. Bright. Quart. Journ. Mi<r. Sci. 8: 95. pi 5.J. 6. ISGO. 

 gKiitz. Sp. Alg. 126. 1819. 



