1888-89.] Mr John Rattray on the Genus Coscinodiscus. 627 
f Markings to 4 in *01 mm., oblique rows 
straight. Apiculi minute or absent, 
I Markings 3J to 4 in '01 mm., oblique rows sub- 
j straight. Border f of radius broad, with dis- 
I tinct striae ; inner and outer parts separated by 
. J a narrow line, ...... 
' | Markings 6 in '01 mm. ; rows straight. Apiculi 
minute. Border narrow, .... 
I Markings 9 in ’01 mm., decreasing but slightly 
outwards, on a narrow band at border 14 to 16 
I in "01mm., oblique rows substraight, . 
I Oblique rows more curved, .... 
'Markings at centre 5 to 6, towards border 10, in 
-4)1 mm. ; robust, decrease outwards rapid. 
Apiculi many, at unequal intervals, 
, -h ! Markings towards centre 2, at border 4 to 6, in 
im j *01 mm.; not robust, decrease outwards rapid. 
Apiculi many, prominent in a circle at border, 
I Decrease in size of markings outwards more 
l gradual, ....... 
f Markings obtusely angular, subpearly, towards 
centre 2J, at border 3, in ‘01 mm. Non- 
apiculate, ....... 
Markings at centre 4, towards border 8, in *01 
-mm.; oblique rows concave outwards. Apicu- 
late, ........ 
Markings in ’01 mm. Border narrow. 
158. -{ (Diam. ‘02), 
Markings towards centre 5, at border 6, in ’01 
mm. Apiculi numerous, distinct. Border 
broad, hyaline, ...... 
Markings at centre 6, at border 9 to 10, in ‘01 
mm. ; oblique rows curved outwards. Apiculi 
j minute. Border narrow, .... 
I Markings otherwise, ...... 
/"Markings towards centre 4, at border 6, in *01 
J mm., secondary larger hexagonal areolse 
j distinct, ....... 
l^No such secondary areolse, .... 
f Markings 8 to 9 in '01 mm. , decreasing somewhat 
| outwards. Centre occupied by .a single, evident 
„„ j circular areola. Apiculi in a circlet at border, 
’ j Markings towards centre 3, towards border 4, in 
'01 mm. No such central areola. Border 
L strise 3 to 4 in *01 mm., .... 
llneatus. 
marginato • lineat us. 
anguste-lineatus. 
sublineatus. 
157. 
decipiens. 
minuens. 
158. 
antimimos. 
excentricus. 
subconcavus. 
peruanus. 
minor. 
159. 
labyrinthus. 
160. 
pseudo-lineatus. 
antiquus. 
ACTIROGONIUM. 
Ehrb. emend., Mon. Ber. Ah ., 1847, p. 54. — Circular or ob- 
tusely angular. Surface with a central area, sometimes distinct. 
Colour pale grey, the rays more pearly. Markings on central 
area areolate, obtusely angular or rounded; rays broad, distinct, 
straight, curved or flexuous, sometimes subclavate, regular or 
irregular, confined to a zone about the semiradius, or extending 
nearer to the border, radiating to the angles of the valve, more 
