1888-89.] Mr John Rattray on the Genus Coscinodiscus. 543 
Yar. duplicata. Grun., Hid., 1884, p. 76. — Diam. *0215 mm. 
Markings hexagonal, placed obliquely so that their lower and upper 
ends are united by oblique walls. — Cleve and Moll., Diat., No. 57. 
Habitat . — Shokoe Hill deposit, Richmond, U.S. (Grunow) ; 
Richmond Ya. (Greville ! Cleve and Moller !). 
Yar. calif ornica, nov. C. calif ornicus, O’Me. MS. — Diam. *22 mm. 
Markings towards the central space 6 to 8, increasing outwards to 
4, again decreasing to 8, in *01 mm. at the border. 
Habitat . — “ Guano ” (O’Meara !); Medway (Dallas!).* 
Yar. guineensis, Rattray. C. guineensis , Grun., Denk. Wien. Ah., 
1884, p. 76. — Diam. *05 to ‘1 mm. Central space distinct. Mark- 
ings hexagonal; towards the centre rounded, granular, 5J in *01 mm., 
not distinctly punctate ; the interspaces provided with small hexa- 
gonally arranged puncta. 
Habitat . — Brackish water, Lagos (Grunow). 
Yar. laxa, nov. C. guineensis, Grun., ibid., p. 76. — Diam. *13 mm. 
Central space round with irregularly placed puncta. Markings free. 
Habitat . — Monterey deposit (Grunow). 
C. Janiscliii. Sch., Atl., pi. lxiv. figs. 3, 4. — Diam. *16 to' '245 
mm. Central space subcircular, hyaline, to of diam. broad. 
Markings faint, but sharply defined, on a narrow band at the border, 
obtusely angular, increasing but slightly outwards, to 4 in -01 
mm., non-punctate, the central dots indistinct ; rows radial, 
secondary rows obscure. — Grun., Denk. Wien. Ak., 1884, p. 76; 
Janisch., Gazelle Exped., taf. iv. figs. 3, 5; C. marginatus , Janisch. 
( non Ehrb.), Abh. Sch. Ges. vater. Cult., 1882, p. 3, pi. i. a. fig. 20. 
This species has sometimes been confounded with C. gigas. 
Habitat.— 11 Guanos ” (Grunow ! Macrae ! Firth !) ; Ichaboe 
guano (Janisch, Joshua! Greville!); Felso-Eszterg&ly, Kekko, 
Szent Peter deposits (Pantocsek !) ; Peruvian guano (Firth !);f 
soundings, Gulf of California (H. L. Smith !) ; J Richmond 
(O’Meara !) ; Chincha guano (Grove !) ; Saldanha Bay guano 
(Cleve, Greville !) ; Cambridge deposit (?) (O’Meara !) ; Java, 
(Cleve !). 
* In the .collection of Dr Greville. 
+ In the collection of Dr F. W. Griffin. 
J H. L. Smith, Diat. Spec. Typ ., No. 91. 
