119 971 
Among the many figures of 4. 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. erassus 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 .4. 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 
van Heurck ].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. (Hupodiscus) 
crassus signed by W. Smith himself. A. (Hupodiscus) crassus W. 5m. 
is referred by Rattray (l.c. p. 173) to the widely distributed .Act. Ehren- 
bergit Ralfs. 
20. A. subocellatus (Grun.) Ratt. A.S. Atl. tab. LVII, fig. 31. 
Solitary in a sample from K Kt. 
Resembles with regard to the striation more Coscinodiscus curvatulus 
Grun. var latius striata Ratt. A. 8. 1. c. fig. 30, but the pseudonodule 
are very evident. 
Area: Bolivian Guano, Cape 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. Coscinodiseus curvatulus Grun. 
21. A. subtilis Ralfs forma subtilissima. Cfr. V.H. Syn. tab. CXXIV, 
fig. 7. 
Surface convex, diam. c. 0,13 mm., rows towards the centrum 
16 in 0,01 mm. ‘ 
K Kt (17 samples). 
Area: the main species ubiquitous. 
Dr. Henri Van Heurck, wo has been kind enough to compare 
the present form with typical 4. subt. from his rich collections, says that 
it differs: 1) par sa forme notablement plus bombé, 2) par sa grande 
minceur et sa fragilité, 3) par sa striation infinement plus fine. Ce serait 
done une forma subtilissima ou une espéce nouvelle trés 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‘. 
