GrevillEj on Neiv Diatoms. 11 
Hab. Deposit at Moron^ in the Province of Seville; 
George Norman^ Esq. 
The discovery of such a species as I have now the privilege 
of describing will provoke the envy of all keen diatom - 
hunters, and I may be pardoned the confession, that to have 
my own name associated with it by my kind friend Mr. 
Norman, is one of those rewards which labourers in the 
field of natural science most highly appreciate. In its 
large size and inconceivably rich decoration, this wonderful 
species stands alone among its congeners. The umbilicus is 
small and irregular ; and in the centre of the disc, for about 
a fourth part of the radius, the compartments are filled with 
verrucose, more or less rounded or oblong, irregularly 
radiating clusters of granules. These gradually pass into 
others more equal in size and more regularly arranged, so 
that they not only radiate, but are beautifully diagonal and 
intersecting. On the little wart-like cushions are clusters of 
four to six coral-like granules, which, when viewed vertically, 
appear like ordinary spherical, brilliant granules, but are in 
fact considerably elong;3.ted, as is shown at the edge of the 
furrows, and, indeed, wherever the surface happens to be so 
undulated as to bring them into an oblique position. The 
furrows are very narrow, slightly widening in their course, 
and suddenly dilating into a small blank space beneath the 
submarginal processes. On each side of the latter are a 
few broad strise, having externally a sort of scalloped outline, 
which does not extend to the middle of the compartment, 
while within the margin itself jx pale circle of fine strise is 
visible, such as exist probably ill all the species. 
Aulacodiscus radiatus, n. sp., Grev. — Disc pale, with very 
minute radiating puncta ; furrows inconspicuous ; processes 
(5) minute, submarginal, surrounded by a broad, somewhat 
oblong, blank space. Diameter '0047"' (fig. 4). 
Hah, Barbadoes deposit, Cambridge estate \ C. Johnson, 
Esq. 
This and the following species possess considerable interest, 
as they appear to form, along with A. pallidus Trans. 
Mic. Soc.,^ vol. xi, p. 72), a section of the genus charac- 
terised by the pale colour, punctiform structure, minute 
processes, and relatively large blank areas in which they are 
situated. The general aspect of the species last mentioned 
is quite lost in the coarseness of the engraved figure. In all 
the three species there is a sort of circular ridge following 
the line of the processes, and upon this ridge some opaque 
markings, which suggest the idea of cellulate structure filled 
■^ith colouring matter ; but the extremely irregular form of 
