1888 - 89 .] Mr John Rattray on the Genus Coscinodiscus. 673 
hyaline striae at right angles to its edge undifferentiated. — (PL III. 
% 17.) 
A specimen occurs in Dr Greville’s collection in the British 
Museum, labelled P. conicus , and another labelled P. major. From 
both of these the present var. is quite distinct. 
Habitat . — “Barbados” (Johnson! Greville!); Cambridge deposit, 
Barbados (Johnson !). 
P. major. Grey., Trans. Micr. Soc. Lond ., 1863, p. 64, pi. iv. 
fig. 2. — Fragmentary. Diam. ? Surface slightly convex. Central 
space subcircular, '0175 mm. broad, hearing almost invisible 
minute puncta, and a large round more distinct slightly excentric 
granule, its outer edge minutely crenate. Markings small, round, 
granular ; towards the central space 8, nearer the border 10, in 
*01 mm.; rows radial, straight, in faint fasciculi, most originating 
at about *015 mm. from the central space, the others proceeding 
from the edge of this space ; interspaces at origin of shorter rows 
hyaline. 
Habitat. — Cambridge deposit, Barbados (Greville !). 
Yar. densa , nov. P. major , Grev., ibid., 1865, p. 46. — Diam. 1 
Central space circular to oval, '0075 to '01 mm. broad, its outer 
edge smooth. Markings subareolate, near the central space 51 to 
6 in '01 mm.; interspaces around the central space more minute. 
—(PI. III. fig. 21.) 
The central space and markings at once distinguish this var. 
Habitat . — Cambridge deposit, Barbados (Johnson !); “ Barbados ” 
(Greville !). 
P. elegans. Grev., Trans. Micr. Soc. Lond., 1863, p. 65, pi. iv. 
fig. 1. — Circular. Diam. '0625 to '095 mm. Surface rounded 
and dome-shaped. Central space circular, *0075 mm. broad, 
sharply defined, hyaline. Markings obtusely angular or sub- 
areolate, decreasing gradually from the central space outwards, 
around the central space 6, near the border 10 to 12, in '01 mm.; 
rows radial, straight; fasciculi distinct; interspaces' minute, largest 
around the central space. Girdle cylindrical, *03 mm. broad, in a 
frustule, '06 mm. in diam.; a narrow hyaline hand at each extremity ; 
vol. xvi. 22/11/89 2 u 
