570 Proceedings of Royal Society of Edinburgh. [sess. 
subequal 4, on the remaining subopaque sharply defined band 
adjacent to the border 6, in *01 mm.; rows inconspicuous, on the 
outer portion of the subopaque band more evident, secondary 
irregular subconcentric rows faint. Border sharply defined, hoop- 
like; strias delicate, 10 to 12 in -01 mm. — (PI. II. fig. 8.) 
Habitat. — Sta Monica, California (Deby !).* 
C. apiculatus. Ehrb., Mon. Ber. Ak ., 1884, p. 77. — Diam. ‘0825 
to *1125 mm. Central space distinct, irregularly rounded, about 
of diam. broad. Markings rounded, often compressed in the 
direction of the radius ; sometimes polygonal, non-punctate, increas- 
ing slightly from the centre to about the semi-radius, again 
decreasing gradually to the border ; towards the centre 4, at the 
border 6 to 8, in '01 mm. Border indistinctly defined on its inner 
side; striae coarse, subregular,. 6 in ’01 mm. — Ehrb., Mikrog ., pi. 
xviii. fig. 43 ; Balfs in Pritch. Inf. , p. 829 ; Grun., Denk. Wien. 
Ak ., 1884, p. 75; Sch., Atl ., pi. lxiv. figs. 5-8; Cleve and Moll., 
Diat ., Nos. 164, 215; Baben., Alg. Europ ., No. 2484; C. apicu - 
latis , var., Sch., ibid ., pi. lxiv. fig. 9 ; C. apiculatus ? Sch., ibid., pi. 
lxiv. fig. 10. 
This species, when its markings are polygonal and in contact, is 
distinguished from C. radiatus , Ehrb., by the presence of a central 
space. Ehrenberg compares it with Pyxidicula gemmifera, Ehrb. 
The specimen figured by Schmidt {Atl., pi. lxiv. fig. 10) has an 
unusually prominent border. 
Habitat. — Rappahannock, Ya. (Bailey ! f Rogers !) ;f Richmond, 
Ya. (Ehrenberg, Kinker !) ; “America” (Ralfs) ; Nottingham, U.S., 
(Cleve and Moller! Hardman !);J “Virginia” (Hardman!); 
Bermuda tripoli (Greville !) ; Delaware, Md. (O’Meara !) ; Mejillones 
(O’Meara!); Patos Island guano (Hardman !); J Los Angelos 
(O’Meara !) ; Richmond tunnel (OMeara !) ; Monkston tidepool 
(O’Meara !) ; Cambridge deposit, Barbados (Greville !) ; Upper 
Peruvian guano (Weiss flog !) ; Piscataway (Weissflog ! Greville !) ; 
Moron deposit (Greville !) ; Monterey stone (Greville !) ; Sta 
Monica deposit (Cleve and Moller !) ; Maryland (Cleve !) ; Laguna 
Harbour, anchor ground (Rabenhorst and Schwarz !). 
* In a Coscinodiscus Type-plate by Thum, in the collection of Julien Deby. 
t In the collection of Dr Greville. 
X In the collection of Julien Deby. 
