1888 - 89 .] Mr John Rattray on the Genus Coscinodiscus. 541 
more prominent ; rows distinctly radial, secondary rows more 
obvious. Border more sharply defined. — C. heterojoorus, var. Grun., 
Sch. in Atl., pi. lxi. fig. 1. 
Habitat. — Moron deposit (Grunow). 
C. boliviensis. Grun., Denk. Wien. Ak., 1884, p. 76. — Diam. 
*15 to ’22 mm. Central space small, irregular. Markings hexagonal, 
non-punctate, increasing gradually outwards for about § of the 
radius; towards the centre 4, at about -| of radius 3 in *01 mm., 
thence decreasing rapidly to the border to 6 in -01 mm.; secondary 
oblique rows inconspicuous. — C. Woodwardii. varj Sch., Atl., 
** pi. lx. fig. 8. 
Distinguished from C. apiculatus , var. ambigua , by the increase 
of the markings outwards, and from C. gigas by their arrangement 
in contact around the centre. The increase in the markings out- 
wards is greater in some specimens than in others. 
Habitat. — Bolivian guano, Sta Monica deposit (Grunow) ; Darien 
(Grunow, Schmidt); Cambridge deposit, Barbados (Hardman!* 
Kinker !) ; Lobos de Afuera guano (Grove !). 
Yar. spinulosa. Grun., ibid., 1884, p. 76; C. boliviensis, 
Grun.; Van Heurck, Syn. Diat. Belg., pi. cxxxii. fig. 4. — Diam. 
*16 to ’17 mm. Central space large, circular, about A of diam. 
broad. Markings towards the centre 5, towards the border 3i in 
•01 mm.; a circlet of numerous minute apiculi close to the border. 
Habitat. — Bolivian guano (Grunow). 
C. gigas. Ehrb., 1841, Abh. Ber. Ak., 1841, p. 412. — Diam. 
*159 to *31 mm., easily seen by the naked eye. Central space 
subcircular, about to of diam. broad. Markings obtusely 
angular, and least crowded towards the centre, with central dots 
faint, soon becoming hexagonal, and increasing gradually outwards ; 
towards the centre 4, towards the border If to 2 in ’01 mm., at the 
border again small ; secondary oblique decussating rows distinct. 
Border narrow ; strise radial, about 4 in ’01 mm., subregular. — Ehrb., 
Mikrog., pi. xviii. fig. 34 ; Ralfs in Pritch. Inf., p. 829 ; Jan., 
Sch. Ges. voter. Cult., 1862, Heft ii. p. 3, pi. 1a. fig. 12; Gazelle 
In the collection of Julien Deby. 
