72 
Greville_, on New Diatoms. 
without inflations_, submarginal ; furrows open, on slightly 
convex ridges_, regularly fringed on each side with shorty gra- 
nular lines. Diameter about '0050". (Fig. 16.) 
Hab. Barbadoes deposit^, from Cambridge estate ; C. John- 
son, Esq. 
Not prismatically elevated in the middle, as in the pre- 
ceding species, but the centre is depressed, and the granules 
irregularly disposed round the umbilicus, some of them, at 
least occasionally, partially concentric. The connecting fur- 
rows form a conspicuous feature, being twice as wide as the 
diameter of the granules. From the two lines of granules 
which define the furrows spring the fringe of short lines, 
given off at right angles so regularly as to be pectinate, and 
which increase in length near the processes and margin, like 
the feathers on a bantam^s legs and feet. 
Aulacodiscus pallidus, n. sp., Grev. — Valve pale, with nu- 
merous (10) processes at some distance from the margin, 
and radiating lines of minute pun eta ; connecting furrows de- 
fined by two rows of puncta. Diameter -0035". (Fig. 17.) 
Hab. Barbadoes deposit, from Cambridge, estate in a slide 
communicated by C. Johnson, Esq. 
At first sight the present species appears to be very unlike 
an Aulacodiscus, but the connecting furrows are sufficient to 
establish its position. There is no umbilical vacancy ; the 
radiating puncta commence at the very centre, and just before 
reaching the circle of processes appear to sink down at an 
obtuse angle to the margin, while the furrows are continued, 
at a slight elevation, to the processes. The latter may have 
been all broken off, as I can perceive merely the oval vacant 
space, and a tubercle within it. 
Aulacodiscus? paradoxus, n. sp., Grev. — Valve divided by 
radiating undulations into six compartments, filled with 
decussating lines of distinct granules, each alternate com- 
partment being in a higher plane than the rest, and pro- 
vided with an intra- marginal_, short process. Diameter 'OO^O". 
(Pig. 18.) 
Hab. Barbadoes deposit, from Cambridge estate,, in slides 
communicated by C. Johnson, Esq. 
I have only seen two specimens of this most remarkable 
diatom, but they are in so good a state as to render their 
examination perfectly satisfactory. The general structure is 
sufficiently characteristic of the genus, but in several points 
of view the valve is anomalous. The equal division into six 
compartments is more like Actinoptychus (Ehr.) and its allies^ 
and the resemblance is rendered more striking in consequence 
of the alternate compartments lying in a different plane. 
