52 
Greville^ on Aster olamprce. 
Of this species,, I have only seen the valve here figured. 
The smooth^ opaque segments^ in which I have been unable 
to trace the slightest punctation^ indicate an approach to 
the subjects of the following section : 
Section II. — Umbilicus occupied by a thick, solid, or more 
or less cribriform or areolated definite nucleus. Umbilical 
lines thick. 
14. Asterolampra cemulans, n. sp., Grev. — Nucleus solid (?) 
or cribriform ; umbilical lines thick ; inner margin of the 
segments furnished with a row of intra-marginal oblong puncta. 
Diameter about 0023". (Figs. 34, 35.) 
Hab. Barbadoes deposit ; rare. 
It is impossible not to perceive in the valve of this species 
a strong likeness to fig. 6 of ^. decora. There is, however, 
in the discs now represented, an unmistakeably definite nu- 
cleus, a thickness of substance and an opacity (except in 
the hyaline area) which is peculiar to themselves and other 
individuals of the present section. Even when the nucleus 
is widely areolate, as in fig. 34, the walls of the areolae are 
thick and unequal, and quite unlike the more delicate um- 
bilical cellulation which often occurs in the species of the 
previous section. In one of the valves of A, (Bmulans, it will 
be perceived that the nucleus is sparingly cribriform; it is 
highly probable that it is sometimes solid. The segments 
have a few puncta scattered remotely over their surface, in 
addition to the intra-marginal oblong ones. The rays are 
numerous, usually about 12. 
15. Asterolampra simulanSj n. sp., Grev. — Nucleus solid 
(always ?) ; umbilical lines thick ; segments with their inner 
margin composed of large oblong ceUules, the lateral ones 
shortly projecting. Diameter '0024''. (Fig. 36.) 
Hab. Barbadoes deposit ; rare. 
This diatom also bears some resemblance to one already 
described : — var. a. of A. vulgaris, represented at fig. 17. The 
segments with their oblong cellules, the lateral ones of which 
project, are almost indentical; and there is, in addition, an 
indication of similar minutely punctate arches in the marginal 
portion of the segments, imperfectly, however, developed. 
Nevertheless, the same important differences exist in this as 
in the preceding species. There is especially the definite, 
solid nucleus, giving off robust, umbilical lines. 
16. Asterolampra Scutula, n. sp. Grev. — Nucleus small, 
solid ; umbilical lines thick ; segments with the inner margin 
thickened, smooth, except a large clavate cellule at each 
angle. Diameter -0019''. (Fig. 47.) 
