544 Proceedings of Royal Society of Edinburgh. [sess. 
Var. arafurensis. Grun., ibid., 1884, p. 76. — Diam. from ’29 
to *425 mm. Markings increasing more from the central space 
outwards ; towards the centre 3^-, towards the border 2^ in ’01 mm. 
— O. arafurensis var., Cstr., Diat. Chall. Exped ., p. 153, pi. ii. fig. 
4; C. craspedodiscus , O’ Me., Quart. Jour. Micr. Sci., 1877, p. 463. 
The presence of the large central space referred to by O’Meara 
in his Coscinodiscus craspedodiscus excludes it from Coscinodiscus 
craspedodiscus , Kiitz., where there is a central rosette, and identifies 
it with the present var. The hoop-like appearance of the valve 
under a low power referred to by Castracane is not shown in his 
figure {Diat. Chall. Exped ., p. 152-154, pi. iii. fig. 5). 
Habitat . — Arafura Sea, H.M.S. Challenger (Grunow, Weissflog ! 
Rae !) ; Gazelle Expedition (Weissflog !) ; Bay of Bengal (Macrae !) ; 
“ Atlantic Ocean ” (Cleve). 
C. entoleion. Grun. Sch., Atl., pi. cxiv. fig. 3. — Diam. *25 to 
•3 mm. Surface slightly convex near the border. Central space 
circular, to Jj- of diam. broad. Markings hexagonal, increasing 
from the central space outwards, again decreasing near the border ; 
towards the centre most delicate, 3 to 2-|, near the border 2 to 2-| 
in *01 mm.; oblique decussating rows evident. Border sharply 
defined, narrow ; striae 4 to 5 in -01 mm. 
Distinguished from C. gigas by the more delicate and smaller 
markings and the absence of narrow hyaline interspaces radiating 
outwards from the central space. Specimens have sometimes been 
confounded with C. perforatus , var. cellulosa , from which they 
differ by the marked increase of the areolae outwards. 
Habitat. — Thames mud, at Southend (Dickie !) ; Hungarian marl 
(Thum).* 
C. flexilis, sp. n. Sch., Atl., pi. cxiv. fig. 6. — Diam. T5 to T2 
mm. Surface almost flat. Central space distinct, Jg- to of diam. 
broad, surrounded by an inconspicuous band of larger areolae. 
Markings polygonal, mostly hexagonal, increasing for a short 
distance outwards from the band surrounding the central space, 
again gradually decreasing towards the border ; towards the centre 
4i to 5, about the semiradius 4, at the border 6, in *01 mm.; rows 
Fide A. Schmidt. 
