1888 - 89 .] Mr John Rattray on the Genus Coscinodiscus. 631 
coronatus , Brightw., Quart. Jour. Micr. Sci ., 1860, p. 95, pi. v. 
fig. 6 . — Diam. J2 to ’185 mm. Central space subcircular, y 1 ^ to 
2 I 3 of diam. broad, sometimes surrounded by a band of evident 
areolae. Markings areolate ; the circlet of large areolae from § to yy 
of radius from centre, within this circlet the markings subequal, 4 in 
■01 mm., in regular, oblique, greatly curved, decussating rows, beyond 
the circlet decreasing and slightly curved outwards from 5 to 8 in 
•01 mm.; minute apiculi at intervals of about ‘0075 mm. sometimes 
visible, inserted close to the border at the outer ends of faint sub- 
hyaline lines. Border striae 12 to 14 in ’01 mm. — B. pulchra, 
Grun,; Van Heurck, Syn. Diat. Belg ., pi. cxxviii. fig. 9; Bot. 
Centralbl., Bd. xxxiv. 1888, Nos. 2, 3, p. 35 ; Grove and Sturt, 
Jour. QueJc. Micr. Cl., 1887, p. 67 ; B. Murray i, Cstr., Diat. 
Chall. Exped.,- 1886, p. 138, pi. x. fig, 2. 
Habitat. — Cambridge deposit, Barbados (Greville! Johnson!); 
Oama'ru deposit (Grove!); Bridgewater deposit, Barbados (Johnson!); 
“Barbados” (Greville! Johnson!). 
Var. radians, nov. — Diam. - 15 mm. Central space obtusely 
triangular, with outwardly convex sides. Markings areolate ; the 
circlet of large areolae about J of radius from centre, beyond this 
circlet the markings decreasing more distinctly outwards from 4 to 
8 or 9 in ‘01 mm.; primary rays evident at intervals of "0075 mm., 
non-costate. — (PI. III. fig. 14.) 
Habitat. — Barbados deposit (Greville!). 
§ 2. Costat^e. 
Costae distinct. 
B. Johnsonii. Ralfs, Trans. Micr. Soc. Bond., 1866, p. 4, pi. i. 
fig. 11. — Diam. *07 to *1075 mm. Central space minute, round or 
angular, a rosette sometimes evident. Markings areolate, some- 
times subcircular towards the centre, with narrow hyaline inter- 
spaces, the circlet of large areolae from -f- to f- of radius from centre, 
within this circlet the markings subequal or somewhat smaller 
towards the centre, 3 in -01 mm., in obscure radial and more 
evident, sometimes irregularly curved or flexuous decussating 
secondary rows, beyond the circlet decreasing gradually outwards 
from 4 to 6 or 6 J in , 01 mm. at border, with evident primary rays at 
