1888 - 89 .] Mr John Rattray on the Genus Coscinodiscus. 659 
Schmidt ( Atl ., pi. xxxviii. figs. G, 7), which belong rather to 
Asterom. heptactis. 
Habitat. — Pancake ice (Pfankuchen Eise), Ice Barrier, Antarctic 
Ocean, lat. 78° 10' S., long. 162° W. (J. D. Hooker); H.M.S. 
Challenger (Deby !). 
Asterom. moronensis, Rattray. Asterolampra moronensis, Grey., 
Quart. Jour. Micr. Sci., 1863, p. 230, pi. ix. fig. 8. — Diam. *06 to 
•075 mm. Centro-lateral area with sides at first almost parallel, 
and then converging rapidly so as to meet about half way between 
centre and apices of compartments, beyond the point of union a 
simple line passing to the centre. Markings : rays sharply 
geniculate at or slightly beyond their middle, . short lateral rami 
passing obliquely outwards from the geniculations ; the compart- 
ments reaching from to •§- of radius inwards, their inner ends 
obliquely truncate, straight or slightly concave towards the centre, 
those adjacent to the subobsolete interval with one side much 
longer than the other; the areolae obvious, decreasing outwards 
from 6 to 10 in *01 mm., the oblique decussating rows straight or 
slightly curved at their inner ends ; the intervals narrow, expanding 
gradually towards their outer ends, which reach close to the 
border, at the middle of the expanded portion a distinct radial 
dark subconical area. — Sch., Atl., pi. xxxviii. fig. 24. 
Habitat. — Moron deposits near Seville (Greville ! Hardman ! 
Herman !) ;* Santa Monica deposit (Hardman ! Deby !). 
§ 3. Excentrici. 
Sometimes elliptical, rarely suboblong. Clear median portion of 
valve sometimes markedly excentric ; the centro-lateral area extend- 
ing beyond the centre often subclavate, sometimes malleiform. 
The subobsolete ray rarely arcuate, the others straight or curved; 
a lunate ridge sometimes visible at outer ends of rays. 
Asterom. wyville-thomsonianus. O’Me., Jour. Lin. Soc. (Botany), 
vol. xv. p. 57, pi. i. fig. 5. — Diam. *06 mm. Central areolate area 
absent. Markings : rays 6, straight ; the compartments 6, five 
equal smaller, reaching about f, the sixth larger reaching about f of 
radius inwards, their inner ends uniformly convex towards the 
* In the collection of Dr R. K. Greville. 
