600 
Proceedings of Royal Society of Edinburgh. [sess. 
Yar. tenuior , nov. C. cocconeiformis , var. Sch., Atl., pi. lviii. 
fig. 27. — Diam. *0425 mm. Hyaline central band narrow, extend- 
ing to the border. Markings in parallel rows on a narrow but 
distinct median area, about the minor axis; at border more 
minute, forming delicate strise. 
Habitat.— Leton Bank (Schmidt). 
It should be noted that specimens described by Grove and Sturt, 
from the Oamaru deposit, under the designation of Triceratium 
coscinoides , are rather triangular forms of Coscinodiscus , and thus 
form a connecting link to the great but heterogeneous groups of 
forms at present classed in the genus Triceratium. 
Species exclus,® vel inquirend^e. 
C.? poly stigma. Ehrb. (Mon. Ber. Ak ., 1843, p. 271), belongs to 
Aidiscus (Rattray, Jour. Roy. Micr. Soc. Lond ., 1888, p. 897). 
CM bifrons , Cstr. ( Diat . Chall. Exped ., p. 156, pi. ii. fig. 1) 
and C.? janus , Cstr. (i ibid ., p. 157, pi. ii. fig. 2), are inadequately 
defined species, which, with more probability belong to Actinocyclus. 
C. craspedodiscus , Kiitz. (Sp. Alg ., p. 126), is Craspedodiscus 
elegans, Ehrb., but distinct from Coscinodiscus craspedodiscus , O’Me., 
and from Craspedodiscus Coscinodiscus , Ehrb. (Mon. Ber. Ak., 1844, 
p. 266 ; Mikrog., pi. xxxiii. 15. fig. 8, &c.). 
C. Auliscus , Kiitz. (Sp. Alg., p. 126), belongs to Auliscus 
(Rattray, Jour. Roy. Micr. Soc. Lond., 1888, p. 896). 
C. Barklyi, Coates (Quart. Jour. Micr. Sci., 1861, p. 138), from 
Yarra Yarra, has been correctly named by Grunow Actinocyclus 
Barklyi. The species was dedicated to Sir H. Barkly, formerly 
President, Royal Society, Melbourne. 
C. ? rudis, Cstr. (Diat. Chall. Exped., p. 162, pi. xxii. fig. 4), 
from the Philippine Islands, belongs to Stephanopyxis. 
C. minimus, Schum. (Schrift. Phys. Oek. Ges. Eonigsb., 1867, 
p. 62, pi. iii. fig. 72). This Baltic specimen is a Cyclotella , and 
approaches Cy. striata, var. baltica, Gran. (Van Heurck, Syn. Diat. 
Belg., pi. xcii. fig. 13), also from the Baltic. 
C. minor, Weisse (Bull. Ac. Imp. Sci. St Petersb., 1855, p. 276, 
pi. i. fig. 4). The Simbirsk valves, so named by Weisse, were 
designated C. polycora by Ehrenberg, and belong to Pyxidicula. 
