1888-89.] Mr John Rattray on the Genus Coscinodiscus. 513 
Border sharply defined, to of radius hroad ; striae distinct, 4 
in *01 mm.— (PI. III. fig. 1.) 
This species does not strictly belong either to the Radiati or to the 
Fasciculati. It is placed here for convenience, since it approaches 
C. robustus in general appearance. 
Habitat.— Sta Maria deposit (Rae !) ; Sta Marta deposit (Doeg !). 
Yar . pidurata, nov. — Diam. *3 mm. Markings angular or subro- 
tund ; surface mottled with dark, mostly quadrangular spots, which 
are somewhat more crowded on the flattened central portion than 
towards the border. Border striae 6 in *01 mm. — (PI. III. fig. 11.) 
Habitat. — Saida Monica deposit (Thum !).* 
C. glaberrimus , sp. n. — Diam. *1 to *1075 mm. Surface flat from 
the centre to about semiradius, thence sloping somewhat steeply to 
the border. Central space and rosette absent. Markings polygonal, 
pearly, suhequal to semiradius, largest about § of radius from the 
centre, thence decreasing to the border, towards the centre 3J, at -J 
of radius 3, in *01 mm.; secondary oblique decussating rows faint. 
Border hroad, with inner edge indistinct; striae 4 to 5 in *01 mm. 
—(PI. I. fig. 19.) 
Distinguished from C. diversus by the presence of a central space 
and the polygonal outline of the markings on the central half of the 
valve. 
Habitat. — Cambridge deposit, Barbados (Rae !). 
C. obscurus. Sch., Atl., pi. lxi. fig. 16. — Diam. '09 to *165 mm. 
Central space minute, sometimes absent. Markings subpearly, 
with central dots evident, increasing but slightly outwards ; towards 
the centre 2|, at about i of radius from centre 2, at the border 4 
to 5 in *01 mm.; secondary oblique rows inconspicuous, at the 
origin of the shorter rpws are small clear spaces, readily overlooked. 
Border striae coarse, 4 to 6 in *01 mm. — Grun., Denk. Wien. Ak., 
1884, p. 74; Cestodiscus obscurus , Van Heurck, Syn. Diat. Belg. f 
pi. cxxix. fig. 4. 
This species is intermediate in the appearance of its markings 
between C. crassus, Bail., and C. radiatus, Ehrb., on the one hand, 
* In the collection of Jnlien Deby. 
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