— 119 — 



Among the many figures of A. monilif. quoted by Rattray (Actinoc. 

 P. 182) only the above by Hantzsch corresponds exactly to the form 

 met with by me. 



Area: ubiquitous. 



19. A. crassus V. H. Syn. tab. CXXIV, figs. 6 & 8. 

 KKm. KKt, LN (4 samples). 



Area: England, Ireland, Belgium, Denmark. 



NB. Rattray (Actinoc. p. 154) gives this species under A. subcrassus 

 Ratt., as he means that W. Smith's A. (Eupodiscus) crassus (W. Sm. 

 Syn. I, tab. IV, fig. 41) cannot be identical with the species figured by 

 vanHeurck 1. c. and referred by him to A. (Eupodiscus) crassus W. Sm. 

 In his Traité des Diat. p. 524 — 25 van Heurck however points out that 

 the form figured by him agrees with original specimens of A. (Eupodiscus) 

 crassus signed by W. Smith himself. A. (Eupodiscus) crassus W. Sm. 

 is referred by Rattray (I.e. p. 173) to the widely distributed Act. Ehren- 

 bergii Ralfs. 



20. A. subocellatus (Grim.) Ratt. A. S. Atl. tab. LVII, fig. 31. 

 Solitary in a sample from KKt. 



Resembles with regard to the striation more Coscinodiscus curvatulus 

 Grun. var latins striata Ratt. A. S. 1. c. fig. 30, but the pseudonodule 

 are very evident. 



Area: Bolivian Guano, Gape of Good Hope, Kerguelen Island, Table Bay, 

 dredgings off Vancouver Island and off Heard Island. 



Probably it is the same form that Cleve (Ind. Ocean & Mal. Archip. 

 p. 32) quotes from Java sub A. Coscinodiscus curvatulus Grun. 



21. A. subtüis Ralfs forma subtilissima. Gfr. V. H. Syn. tab. CXXIV, 

 fig. 7. 



Surface convex, diam. c. 0,13 mm., rows towards the centrum 

 16 in 0,01 mm. 



KKt (17 samples). 



Area: the main species ubiquitous. 



Dr. Henri Van Heurck, wo has been kind enough to compare 

 the present form with typical A. subt. from his rich collections, says that 

 it differs: „l)par sa forme notablement plus bombé, 2) par sa grande 

 minceur et sa fragilité, 3) par sa striation infmement plus fine. Ce serait 

 donc une forma subtilissima ou une espèce nouvelle très proche du sub- 

 tilissima que j'en ferais" ; but Dr. Van Heurck adds „ n'ayant vu qu'une 

 seule valve, je ne voudrais pas porter une jugement absolu, avant de faire 

 cela il faudrait voir et comparer un certain nombre de valves". 



According to Rattray (Actin. p. 188) the size of the typical species 

 is 0,0498 mm.— 0.0757 mm. ; the present form is nearly twice as large, 

 but Dr. H. Van Heurck has sent me some photographical copies of an 

 Actinoc. subt. from Sandwich Islands which had the same size; further 

 Dr. Van Heurck tells me that he has specimens from the same place 

 which are „ encore notablement plus grandes". 



