1888-89.] Mr John Rattray on the Genus Coscinodiscus. 
Markings at centre 6 to 7, at semiradius 5 to 5-|, 
on a sharply defined marginal band (g of radius 
broad) 10 in ’01 mm. ; rows on marginal band 
oblique, decussating, 
Markings towards centre 4, increasing outwards 
to 2 or 3, at border 4 or 5, in "01 mm. , secondary 
oblique rows indistinct, ..... 
Markings 3^, subequal to semiradius, at § radius 
3 in ‘01 mm., thence decreasing to border. 
Border broad, striae 4 to 5 in *01 mm , . 
Markings towards centre 3, decreasing outwards 
to 5, at border 8, in '01 mm. ; secondary oblique 
rows evident, ...... 
Markings towards centre 3 to 3J, towards border 
4, in ’01 mm. Surface convex, 
/ Apiculate, ^ . 
' \ Non-apiculate, ....... 
'Apiculi robust, spine-like, with blunt free ends 
inserted at middle of small round hyaline 
spaces. Markings round, granular, 6 in 
*01 mm., subpunctiform towards border. 
Central space small, ..... 
Apiculi robust, 6, symmetrical, free ends 
blunt. Markings round, granular, 4 in 
*01 mm., subequal. Central space absent, 
Apiculi distinct. Valves dissimilar — the one 
with markings round, granular, 3 in *01 mm., 
on a submarginal band 8 in ’01 mm., and in 
oblique decussating rows, interspaces distinct 
— the other with markings angular, without 
interspaces, ....... 
Apiculi evident, about *015 mm. apart. Mark- 
ings round, granular, about 5 in *01 mm., 
toward border smaller interspaces hyaline, 
largest towards centre, ..... 
Apiculi conspicuous in a circlet some distance 
from border. Markings granular, secondary 
rows irregularly concentric, interspaces hyaline, 
distinct, ....... 
Apiculi distinct, a circlet close to border, within 
this a few scattered apiculi forming an irregular 
inner circlet. Markings 6 to 10 in ’01 mm., . 
Apiculi in two circlets, those of the inner promi- 
nent, distant, and at opposite sides of valve 
replaced by a narrow curved hyaline band, 
those of the outer minute, close. Markings 
(_ 16 in *01 mm., ...... 
f Markings in radial ■ rows separated by wide 
cuneate interspaces. Border sharp, striae 
obvious, ....... 
Markings small, on a zone adjacent to border 
punctiform, interspaces wide, smaller towards 
border, rows obscurely radial towards centre, 
obviously radial near border, .... 
Markings decreasing gradually outwards, towards 
centre 4 to 4^ in ’01 mm., at border puncti- 
form ; rows radial, those reaching centre few, 
on a narrow band at border many, . 
Markings round for \ to f of radius, on outer 
portion polygonal 2J to 3, at border 6, in 
l ’01 mm., 
57. 
58 . 
exutus. 
argus. 
glaberrimus. 
convexus. 
asperulus. 
57. 
58. 
johnsonianus. 
stokesianus. 
superbus. 
evadens. 
plicatulus . 
lacustris. 
ludovicianus. 
duriusculus. 
agapetos. 
subdivicus. 
diversus. 
