1888-89.] Mr John Rattray on the Genus Coscinodiscus. 577 
originating sharply at or near the semiradius, rarely nearer the 
central space, and terminating at inner edge of the marginal striae. 
Border sharply defined, hyaline. 
Habitat. — Elesd deposit (Hardman !).* 
C. tenuis , Rattray. Cosmiodiscus tenuis , Grun.; Van Heurck, Syn. 
Diat. Belg ., pi. cxxv. fig. 13. — Diam. -055 to -0675 mm. Surface 
slightly convex towards the border. Central space circular, obscure 
or subobsolete. Markings faint, minute rounded granules most 
evident and most laxly disposed towards the centre ; about the 
semiradius 6 in *01 mm., towards the border punctiform, arranged 
in straight radial striae, 8 to 10 in - 01 mm.; between the striae, at 
subregular intervals, narrow, short, indistinct, hyaline spaces. 
Border distinct, from to fa of radius broad ; striae delicate, 
obscure, 16 in *01 mm. 
Habitat. — Monterey deposit (Yan Heurck) ; San Pedro (Grove !). 
C. evadens, sp. n. Sell., Atl., pi. lvii. fig. 44. — Diam. -0625 mm. 
Central space and rosette absent. Markings rounded, granular, 
about 5 in *01 mm., towards the border smaller; interspaces 
hyaline, unequal, largest towards the centre ; rows straight ; apiculi 
evident at intervals of about ’015 mm., inserted at inner edge of 
border. Border sharply defined, narrow ; striae radial, 6 to 8 in 
*01 mm. 
Habitat . — Springfield deposit, Barbados (Schmidt). 
Yar. parvula. Sch., Atl., pi. lvii. fig. 45 (no name). — Diam. 
*0325 mm. Markings subequal to border, non-apiculate. Border 
less sharply defined ; striae short, but distinct, 6 in ‘01 mm. 
Habitat. — Springfield deposit, Barbados (Schmidt). 
C. undatus, Grun. Pant., Fossil. Bacil. Ung., p. 74, pi. x. fig. 
89 ; pi. xxvii. fig. 252. Actinocyclus ( alienus , Grun. varj) undatus, 
Cleve, Jour. Queh. Micr. Cl., 1885, p. 174, pi. xiii. fig. 14. — Diam. 
*07 to ’1 mm. Surface with two concentric elevations and depres- 
sions. Central space indistinct, circular, about fa of diam. broad, 
with rounded isolated granules. Markings rounded, granular, 5 to 6 
in '01 mm., near the border punctiform ; rows separated by narrow 
* In the collection of Mr Julien Deby. 
VOL. XVI. 29/10/89 2 O 
