1888 - 89 .] Mr John Rattray on the Genus Coscinodiscus. 647 
A. vulgaris , var. a, Grev., ibid, 1862, p. 47 ; A. vulgaris, var. b, 
Grev., ibid., p. 47, pi. vii. fig. 21 ; Eul., Diat. Spec. Typ., No. 16. 
Rarely in valves from Cambridge deposit, Barbados, the areolae 
on the central area are unequal and much larger, from 1J to 1-J in 
*01 mm., and are disposed subconcentrically towards its outer 
margin. 
Habitat. — Barbados deposit (Greville ! Hardman ! Eulenstein !) 
locality ? (Deby !) ; Springfield deposit, Barbados (Hardman !) ; 
Cambridge deposit, Barbados (Hardman !) ; Oamaru deposit (Grove ! 
Deby !). 
Yar . planior. A. vulgaris, var. c. Grey., ibid., 1862, p. 47, pi. 
vii. fig. 22. — Diam. *07 mm. Central area distinct, subcircular, 
from to -J of diam. broad. Markings on central area 2J to 3 in 
•01 mm., unequal; the compartments reaching about T 2 T of radius 
inwards, the largest centro-lateral areolae but slightly protuberant, 
sometimes bulging laterally towards their inner ends ; the intervals 
clavate, their outer ends convex, close to the border. 
Habitat.— -Barbados deposit (Greville ! Grove !). 
Yar. cellulosa. A. vulgaris, var. d. Grev., ibid, 1862, p. 47, 
pi. vii. fig.- 23 ; pi. viii. fig. 24. — Diam. -055 to *1 mm., central area 
subcircular, from J to f- of diam. broad, a central rosette sometimes 
distinct. Markings on central area subequal, 4 in '01 mm., without 
order or in obscure oblique decussating rows ; the compartments 
reaching from ^ to f of radius inwards, the band of areolae at their 
inner ends extending outwards almost to border, about 4 in *01 
mm. across ; the marginal areolae protruding slightly at their central 
inwardly convex ends. 
Habitat. — Barbados deposits (Greville ! Deby ! Grove !). 
A. decorata. Grev., Trans. Micr. Soc. Lond ., 1862, p. 46, pi. 
vii. fig. 13. — Diam. *08 mm. Central areolate area absent. Mark- 
ings : rays straight, the compartments reaching about J of radius 
inwards, their inner ends transversely truncate, bounded by a single 
band of oblong areolae 2 to 2J in *01 mm. broad and about *01 mm. 
long, those opposite the rays with long axis radial, the others be- 
coming more and more oblique, those at the angles of the 
compartments *0175 mm. long, with outer ends attenuated ; the 
