1888 - 89 .] Mr John Rattray on the Genus Coscmodiscus. 483 
cesses: “die dunkeln Elecke am Rande entstehen dadurch, dass 
sich je 2 bis 3 Zellchen mit Schalensubstanz fiillen.” 
Habitat . — Sta Monica deposit (Grunow) ; Cambridge deposit 
Barbados (Johnson !). 
C. isoporus. Ehrb., Mikrog ., pi. xxxiii. 17. fig. 3. — Diam. about 
•055 mm. Central space and rosette absent. Markings large, 3| 
to 4 in *01 mm., distinct, subequal to the circumference; rows 
radial, subfasciculate ; secondary concentric rows evident. — Ralfs in 
Pritch. Inf “, p. 830. 
Differs from C. concavus in the absence of a distinct border, and 
the concentric arrangement of the markings, and from C. patina , 
Ehrb., by the reduction in size, in the latter, of the markings 
around the evident clear border and their less conspicuous con- 
centric arrangement. 
Habitat. — Rappahannock Cliff, Virginia (Ebrenberg). 
C. Payeri. Grun., Denk. Wien. Ak., 1884, p. 80, pi. iii. (C), figs. 
12, 13. — Diam. -024 to *03 mm. Central space small, about of 
diam. broad, irregular. Markings around the central space rounded, 
elsewhere angular, often quadrilateral ; central papillae distinct, 
towards the central space 5 or 6, at the border 9 in *01 mm.; 
rows radial, in inconspicuous fasciculi. 
Habitat. — Franz Josefs Land (Grunow). 
Var. subrepleta. Grun., ibid., 1884, p. 80, pi. iii. (C), figs. 14, 15. 
— Diam. *034 mm. Central space subobsolete, or with small round 
isolated granules. Markings smaller, 4J to 5 in '01 mm., a band 
of small granules adjacent to the border. 
Habitat. — Franz Josefs Land (Grunow). 
C. hyalinus. Grun., Denk. Wien. Ak ., 1884, p. 108, pi. iii. (C), 
fig. 28. — Diam. ’025 mm. Central space minute, inconspicuous, 
bearing isolated puncta. Markings punctiform, subequal, 24 in -01 
mm. ; rows radial to subparallel in inconspicuous fasciculi; apiculi 
numerous, distinct, in a single circlet. Border broad, hyaline. — 
Cleve and Moll., Diat ., No. 315; Odontodiscus hyalinus , Grun., 
Kon. Sv. Vet.-Ak. Ilandl. Stockh., 1879, p. 113. 
Distinguished from C. bioculatus by the absence of the two 
conspicuous central granules and the more numerous apiculi. 
