1888-89.] Mr John Rattray on the Genus Coscinodiscus. 461 
the border 4 to 6 in *01 mm. ; radial rows 6, inconspicuous, the 
oblique decussating rows straight or slightly curved ; apiculi 
numerous, prominent, forming a circlet close to the border at short 
intervals. 
The general arrangement of the markings resembles somewhat 
that of C. excentricus , but is less regular, the areolae too are larger, 
and decrease more rapidly to the border. 
Habitat .• — Philippine Islands, H.M.S. Challenger (Castracane). 
C. antimimos * sp. n. — Diam. *08 mm. Markings round or 
bluntly angular, subpearly, towards the centre 2 J, decreasing gradu- 
ally outwards to 3 in ’01 mm.; central papillae obscure; radial rows 
few, inconspicuous; secondary oblique, decussating rows distinctly 
concave towards the border ; non-spiculate. Border striae evident, 
6 in *01 mm., short. — Cleve and Moll., Diat ., No. 257. — (PI. II. 
fig. ii.) 
Distinguished from C. excentricus by its much larger subpearly 
markings. 
Habitat. — North Carolina (Cleve and Moller !). 
C. antiquus. 0. ( excentricus , varJ) antiquus , Grun., Denk. Wien. 
Ah., 1884, p. 84., pi. iv. (D), fig. 24. — Diam. '0565 mm. Mark- 
ings hexagonal, conspicuous, decreasing from the centre out- 
wards ; towards the centre 3, towards the border 4 in *01 mm.; 
oblique, decussating rows substraight or slightly concave out- 
wards ; non-apiculate. Border sharply defined; striae evident, 
distant, 3 to 4 in '01 mm. — C. concavus, Ehrb., Mikrog., pi. xxi. 
fig. 4 (not pi. xviii. fig. 38) ; C. concavus , Greg., var., Sch., Atl., 
pi. lix. fig. 16. 
Differs from C. excentricus in its larger markings and more 
distinct border. 
Habitat. — Mors deposit, Monterey tripoli (Grunow). 
C. excentricus. Ehrb., Abli. Ber. Ak. f 1839, p.146. — Diam. '0525 
to *0825 mm. Surface flat. Markings polygonal, towards the centre 
4, gradually decreasing towards the border to 8 in *01 mm., at the 
centre a single areola surrounded by 5 to 8 similar ones, whence 
inconspicuous radial rows proceed to the border, the oblique decus- 
avrlfufMos, imitating. 
