1888 - 89 .] Mr John Rattray on the Genus Coscinodiscus. 539 
border. Central space angular, about t 3 q of diam. broad. Markings 
rounded, adjacent to the central space, elsewhere polygonal, 2J to 
3 in ‘01 mm., subequal for about § of radius, thence decreasing 
slightly to the border, smooth; secondary oblique rows inconspicuous. 
Border indistinctly defined ; striae somewhat irregular, 4 to 6 in 
*01 mm. — C. crassus , Bail. var. % Grun., Denk. Wien. Ak., 1884, 
p. 74. 
Habitat. — Springfield deposit, Barbados (Schmidt). 
C. cingulatus. Ehrb., Mon. Ber. Ak ., 1844, p. 200. — Diam. 
'049 mm. Central space small, hyaline, indistinct. Markings 
minute, about 13 in - 01 mm. Border smooth, distinct. — Ehrb. 
Mikrog ., pi. xxxv. a. 21. fig. 6; Ralfs in Pritch. Inf., p. 829. 
In Antarctic diabomaceous gatherings I have not observed speci- 
mens similar to this. Is it possible that Ehrenberg was dealing 
with a valve of C. subtilisl 
Habitat. — Antarctic Ice Barrier, lat. 78° 10' S., long. 162° W. 
(Hooker !).* 
C. crassus. Bail., Amer. Jour. Sci., 1856, pi. xxii. p. 4. — Diam. 
•12 to *14 mm. Central space small, angular to elliptical. Mark- 
ings subpearly ; towards the centre 3, towards the border 2 to 2 \ 
in *01 mm., at the border suddenly smaller, secondary oblique rows 
inconspicuous. Border striae 4 in *01 mm. — Ralfs in Pritcli Inf., 
p. 830; Grun., Denk. Wien. Ak., 1884, p. 74. C. crassus , var., Sch., 
Atl., pi. Ixi. fig. 19. 
Grunow, in his synopsis of this genus {Denk. Wien. Ak., 1884, 
p. 71), states correctly in his section 15 that the markings become 
smaller both towards the centre and towards the border, but 
erroneously states in the following section (16) that only the outer- 
most markings are smaller, and by this means he differentiates this 
species. 
Habitat. — Soundings, Sea of Kamtschatka (Bailey) ; Monterey 
(Bailey); Kekko, Szakal and Dolje deposits (Pentocsek !) ; Barbados 
(Cleve !). 
Yar. morsiana. Grun., ibid., 1884, p. 74. — Diam. J74. Mark- 
* Fide Ehrenberg. 
