260 0NTBIBUT1ON6 PROM Nil NATIONAL BEBBABIUM. 



Coseinodiaeui woo d w a rdii Bulen. Diat. Bp. Typ. do. 116. 1868. Schmidt Atlas 



pi. ' 1878; pi ' , I 1881. 



I do ii"i find satisfactory reason for placing this diatom under ( . a pint lain* Ehrenb. 

 as is done b) Rattray*" and copied in I>-- Toni.* Although our knowledge of the latter 



species ia mosl obscure, ye1 bo far as the form ia now represented n baa only a re te 



resemblance to the above. Ii» typical structure ia with beaded valves, while the 

 above ia covered with a fine network; and although the transition from beada to hexa- 

 gona by the enlargement of the beading and their Bubsequenl lateral pressure ia an 

 easily understood on< . I think the form ia then bo far from the type as to have ; 

 over into another species. Rattray has, I think, suggested a more important affinity 

 than the one above by hie remark* thai C. apiculatus "when its markings are polygonal 

 and in contact is distinguished from C. radiatus Ehrenb. by the presence of a central 

 space." Thie ia very nearly the Btructure represented by C. woodwardii, which I 

 would therefore prefer to place aa a variety of C. radiatus rather than to unite ii 

 w nh C. apiculatus, aa I Look upon the minute and irregular central area of thie species 

 as less significant than the striking structural contrast between ii and C. apiculatus. 

 I'>.M for the present al leasl ii is better to keep this species independent, as is done by 

 ( rrunow, Schmidt, and others. Eabirshaw makes this name synonymous with C. argus 

 Ehrenb., an identification quite oul of the question. 



Found al Btation 2694H, off California. 



ACTINOCYCLUS Ehrenb. 



Actinocyclus Ehrenb. Ber. Akad. Wiss. Berl. 1837: 61. L838; [nfus. 171. L838; Ber. 



Akad. Wiss. Berl. 1840: 202 204. L841. 

 Pyridicula Ehrenb. in part; Ber. Akad. Wiss. Berl. 1844: 86. L846. 

 Eupodiscus Ehrenb. in pari: W. Smith, Synop. Brit. Diat. 1: 24. pi. ',./. .;/. L853. 



Breb. Journ. Quek. Micr. Club 2: 71. L870. Greg. Trans. Roy. Soc. Edinb. 21: 



501. L857. 

 Actinoptychus Ehrenb. in pari: Ehrenb. Mikrog. pi. 18. f. 12. L854. Kiitz. Bacill. 



L34. L844. Bright. Quart. Journ. Micr. Sci. 8: 94. L860 

 Auliscus Ehrenb. in pari: Rabh. PL Eur. Alg. 1: 320. L864. 

 Hyalodiscus Ehrenb. inr part; II. I.. Smith, Amer. Journ. Micr. 2: LOO. L877. 

 Stictodiscus Grev. in part; Grun.; Van Eeur. Synop. pi. 118. f. 4- 1881. 

 Podosira Ehrenb. in part; Grun.; Van Hour. Synop. pi. 118. f. 5. L881. 

 Micropodiscus Grun. ; Van Eeur. Synop. pi. 118. f. 5. L881. 

 Roperia Grun.; Grun in Van Eeur.' Synop. />l. 118. f. 6. note. L881. Ratt. Journ. 



Roy. Micr. Soc. 8-': 917. L888 

 Coscinodiscus Ehrenb. in part; Grun.Denksc.hr. Akad. Wien 48 2 : B3. 1884. Norm. 



Trans. Micr. Soc. Lond. n. b. 9: 7. L861. Grove, Proc. Roy. Soc. Edinb. 17: i 19. 



L890. 



This genus i- <<wc of extreme difficulty first . because of the remarkable confusion 

 between it ami other genera, especially in the earlier writers: the result being that 

 -inl i actinocycloid forma as are treated by them are difficult to find. This is especially 

 the case in regard to this genus and Actinoptychus Ehrenb., on i lie pari of Ehrenberg, 

 Ki'ii/inir. Greville, Brightwell, and others, a condition growing out of the fact that 

 when Ehrenberg firsl constituted the genua Actinocyclus it made no distinction 

 between these and the Actinoptychus forms, which, though bo dissimilar, were not 

 separated until L840, when Ehrenberg created the genua Actinoptychus for that pur- 



Proc. Roy. Soc. Edinb. 16: 571. L8* 

 b De Toni, Syll. Alg. 2: L283. L894. 

 ■ I >p. cit. 570. 



