1888 - 89 .] Mr John Rattray on the Genus Coscinodiscus. 555 
fathoms, by H.M.S. Challenger (Rae !) ; Bally brack (O’Meara !) ; 
Nottingham, Maryland, (O’Meara !) ; Cambridge deposit, Barbados 
(Johnson !).* 
Yar. dentata , nov. — Diam. ’1075 mm. Central rosette small ; 
markings towards the centre 4, at the border 6, in *01 mm.; 
apiculi large, at subequal intervals of about -006 mm. 
Habitat. — A (Greville !) ; Barbados deposit (Johnson !).* 
C. centralis , emend.; G.? centralis. Ehrb., A bh. Ber. Ak ., 1838, 
p. 129. — Diam. -12 to *255 mm. Central space absent or minute; 
a rosette obvious. Markings variable in size, subequal — 4 to 4J in 
‘01 mm. for about of the radius, thence decreasing gradually 
outwards on the outer sometimes 5 in ‘01 mm., and decreasing 
gently from the semiradius ; rows straight, sometimes subfasciculate 
towards the border, the fasciculi separated by narrow clear areas 
proceeding inwards from the apiculi ; apiculi delicate, inserted at 
the border at intervals of about ‘006 mm., 2 larger unsymmetrical, 
at an interval from each other somewhat greater than the semiradius. 
Border narrow; striae 6 in ‘01 mm. — Ehrb., Mon. Ber. Ak. 1844, p. 78 ; 
Mikrog ., pi. xviii. fig. 39; pi. xxii. fig. 1; Greg., Trans. Roy. Soc. 
Edin ., 1857, p. 501, pi. xi. fig. 49 ; Ralfs in Pritch. Inf., p. 828 ; 
Grun., Sitzungsb. naturw. Ges. Isis , Dresden , 1878, p. 123 ; Van 
Heurck, Syn. Diat. Belg., pi. ciii. fig. B ; H. L. Smith, Diat. Spec. 
Typ., Nos. 91, 92 ; Cleve and Moll., Diat., Nos. 57, 164, 207, 215 ; 
C. aster omphalus, var. centralis, Grun., Denk. Wien. Ak., 1884, p. 79; 
C. centralis, var. micraster, Grun.; Cleve and Moll., Diat., No. 172 ; 
G. centralis , var., Cstr., Diat . Chall. Exped. , p. 155, pi. ii. 
fig. 3 ; G. centralis forma minor, Van Heurck., Typ. Syn. Diat. 
Belg., No. 531 (excl. G. centralis ,f Weisse, Bull. Acad. Imp St 
Petersb., 1867, p. 122, pi. i. fig. 18 ; G. centralist O’Me., Proc. 
Roy. Irish Ac. 1875, p. 260, pi. xxvi. fig. 19; G. centralis, § 
Sch., Atl., pi. lxiii. fig. 1 ; C. centralis, Ehrb., Mikrog., pi. xxi. 
fig. 3). 
This species is sometimes confounded with C. oculus-iridis, G. 
* In the collection of Dr Greville. 
t This is C. radiatus, Ehrb. 
X This is probablly G. subtilis, as stated by Grunow. 
§ This is C. . aster omphalus, var. hybrida, Grun . 
