550 
Proceedings of Royal Society of Edinburgh. [sess. 
at two somewhat distant points. — C. omphalanthus , Ehrb.; Ealfs in 
Pritch. Inf . , p. 828 ; Cleve and Moll., Diat., Nos. 57, 215 ; Ehrb., 
Diat. Spec. Typ ., No. 6 (excl. Sch., pi. lxiii. fig. 2). 
The constriction at the border is similar to that of C. biangidatus 
(Sch., Atl ., pi. lxiii. fig. 13), but the latter is devoid of a rosette, 
and the dark band at the border is relatively much wider. This 
var. is frequently mistaken for C. ocidus-iridis, and sometimes for 
C. borealis. 
Habitat. — “Bermuda” (Eulenstein ! * Greville !) ; Nottingham 
deposit (G. M. Brown ! Firth ! Cleve and Moller ! O’Meara ! 
Cleve! Hardman !);f Bichmond, Ya. (O’Meara! Cleve and Moller!); 
Maryland (O’Meara! Hardman!); “Virginia” (Hardman!); Calvert, 
county Maryland (Kinker ! Weissflog!); Kekko deposit (Grove l); 
Rappahannock (Greville !) ; Piscataway deposit (Cambridge ! f 
Greville !) ; Delaware, U.S. (Cambridge !) ; f Patuxent earth 
(Rae !) ;f Holland’s Cliff (Cleve !) ; San Benito deposit, California 
(Grove !). 
Yar. brightwellioides. Grun., ibid ., 1884, p. 78. — Diam. T125 to 
*26 mm. Surface rising from the centre to the semiradius, thence 
descending to the border. Markings polygonal, gradually increasing 
outwards to the semiradius, where there is a distinct circlet of large 
areolae, 2J in *01 mm. at right angles to the radius, thence decreas- 
ing to the border; at the centre 3J, at the semiradius 3, at the 
border 3 in *01 mm. — Pant., Fossil. Bacil. Ung ., p. 71, pi. xvii. 
fig. 155. 
The circlet of larger markings forms a transition to C. bidliens , 
Sch., and to the genus Brightivellia. 
Habitat . — Santa Monica deposit (Grunow, Kinker !) ; Szakal and 
Szent Peter deposits (Pantocsek). 
Yar .pulclira. Grun., ibid., 1884, p. 78. — Diam. -36 mm. Central 
space smooth, *01 mm. broad, surrounded by a distinct band of 
larger markings. Markings 2 to 2J in *01 mm., decreasing quite 
close to the border. 
* As to this locality, Eulenstein notes — “Locus dubius, verisimiliter ad 
pagum hujus nominis Americse borealis non ad insulas referendus. ” 
t In the collection of Dr Griffin. 
