1888 - 89 .] Mr John Rattray on the Genus Coscinodiscus. 531 
mm., decreasing slightly to the border ; irregular on a small central 
area, elsewhere the rows radial, sometimes subfasciculate ; secondary 
oblique decussating rows obvious ; apiculi numerous, forming a 
circlet placed some distance from the border. Border distinctly 
defined, about Jg- of radius broad; striae distinct, 5 or 6 in ’01 mm. 
Habitat. — Yokohama (Schmidt). 
C. denticidatus. Cstr., Diat. Chall. Ex]oed., p. 155, pi. iii. 
fig. 8. — Diam. *13 mm. Surface slightly convex, on outer of 
radius. Central space and rosette absent. Markings polygonal, 
subequal, 8 in *01 mm.; central dots distinct; apiculi scattered 
over the surface at irregular wide intervals, distinct. Border 
sharply defined; striae 8 to 10 in *01 mm. 
This species is nearly allied to C. radiosus , but differs in the 
more uniform markings and in the apiculi Compare also Podosira 
hormoides, Mont. ( = Melosira nummuloides , Ehrb.) from Lima 
(Van Heurck, Syn. Diat. Belg ., pi. lxxxiv. fig. 3). 
Habitat . — Pacific Ocean (Castracane). 
C. imjpressus, Grun. Van Heurck, Syn. Diat. Belg., pi. 
cxxxii. fig. 5. — Diam. ‘08 mm. Surface with a long depression 
near the centre. Central space minute, irregular, about ~ of 
diameter broad. Markings increasing gradually from the margin 
of the central space to the border ; towards the centre 8, toward 
the border 7, in *01 mm.; secondary oblique rows indistinct. 
Border striae, subregular, distinct, 8 to 10 in *01 mm. — Grun., 
Denk. Wien. Ah., 1884, p. 73. 
Habitat . — Sta Monica deposit (Grunow). 
C. coneinnus. W. Sm. Syn., Brit. Diat., ii. p. 85. — Diam *062 
to ’35 mm. Surface somewhat convex. Central rosette of large but 
delicate areolae, sometimes inconspicuous, *0075 to *01 mm. broad. 
Markings polygonal, delicate, most evident towards the centre, where 
there are 7 or 8 in ’01 mm., decreasing outwards to 12 in -01 mm.; 
rows obscurely fasciculate ; near the border at subequal intervals short 
narrow radial clear areas, whence faint subbyaline lines proceed 
inwards ; a circlet of apiculi at the border, minute ; 2 larger apiculi 
unsymmetrical close to the border, a few long acicular apiculi also 
sometimes present on a zone within the processes. — Roper, Quart . 
