1888 - 89 .] Mr John Rattray on the Genus Coscinodiscus. 457 
C. (?) venulosus , Cstr. Diat. Chdll. Exped ., p. 162, pi. xvii. 
fig. 1. — Diam. *034 mm. Central space rounded, about -J- of 
diam. broad. Markings consisting of a few wavy lines diverging 
outwards from the central space, and confined to the central half of 
the valve. 
Habitat. — South of Kerguelen Island (Castracane). 
§ II. Cestodiscoidales. 
Cestodisci , Pant., Fossil. Bacil. Ung ., p. 73. — Circular, rarely 
elliptical. Central space small or absent; no rosette. Markings 
round or angular, cestodiscoid ; rows fasciculate or radial, a 
distinct band adjacent to the border frequent ; valves sometimes 
dissimilar ; apiculi few or more numerous. Border striae usually 
distinct. 
C. proteus , Rattray. Cestodiscus proteus , Hardman ; Van 
Heurck, Syn. Diat. Belg., pL cxxvi. fig. 8. — Diam. *035 to ’09 mm. 
Surface slightly convex. Central space minute. Markings rounded, 
granular, decreasing slightly from the centre outwards, towards the 
centre 6 in *01 mm., on a marginal zone about -I to -J of radius 
broad, sub-punctiform ; rows fasciculate, those composing each 
fasciculus parallel to the radial row at its middle, the inter- 
fasciculate radial rows most prominent between the centre 
and semi-radius, secondary oblique decussating rows on the 
marginal zone only and conspicuous ; interspaces hyaline, largest 
opposite the ends of the shorter rows; apiculi 6 to 12 inter- 
fasciculate, large, inserted a short distance from the border. 
Border indistinctly defined, striae evident uniform, 8 in *01 mm. 
Habitat. — Naparima deposit^ Trinadad (Van Heurck, Grove !). 
C. stokesianus, Grun. Pant., Fossil. Bacil. Ung., p. 73. — Diam. 
*075 mm. Central space absent. Markings rounded, granular; 
about 4 in *01 mm., subequal ; interspaces narrow, most evident at 
origin of shorter rows ; rows radial, straight ; apiculi 6, symmetrical, 
free ends blunt, inserted near inner edge of border. Border sharply 
defined, about -Jg- of radius broad, striae evident, 6 in - 01 mm. — 
Cestodiscus stokesianus , Grev., Trans. Mic. Soc. Lond, ., 1866, p. 
123, pi. xi. fig. 4; Coscinodiscus stokesianus forma minor , Grun., 
