72 
Greville^ on New Diatoms. 
occur. This diatom is subject to occasional distortion,, 
several examples having occurred to me in which the sides 
were of very unequal lengths. 
Triceratium Browneanum, n. sp., Grev. — Small; valve with 
straight sides and rounded angles with obscure pseudo- 
nodules ; surface filled up with small, round, equal, irregularly 
disposed granules. Distance between the angles about 0020". 
{Fig. 16.) 
Hub. In mud, Savannah, Georgia, U.S. 
Probably not a rare species, as it occurs tolerably abundantly 
in a slide kindly communicated to me by my friend, Mr. 
George Mansfield Browne, of Liverpool. It is well marked 
by the equal size throughout the entire valve of the round 
granules, which, although not crowded, are rather closely 
situated. The angles are thickened, but can scarcely be said 
to possess a pseudo-nodule. 
Triceratium ? blanditum, n. sp., Grev. — Sides of valve deeply 
concave ; angles broadly rounded ; centre with a small, blank 
space ; granules conspicuous, subremote, equal, forming 
straight, equidistant, parallel lines. Distance between the 
angles in the four-angled frustule 0020". (Fig. 17.) 
Hah. Barbadoes deposit ; excessively rare. 
A very striking object, which I introduce with some hesita- 
tion as a Triceratium. Amphitetras, however, is now ad- 
mitted to be separated from that genus by a very slender 
line. I have seen only two frustules, both of which are 
four-angled, and very conspicuous for the equal size of the 
granules, their equidistance, and the perfectly straight, 
parallel lines in which they are arranged. The small, circular, 
blank space is only defined by the absence of granules. 
There is also a small, vacant space opposite to each concavity 
of the valve. This species may have some affinity with 
Amphitetras parallela of Ehrenberg, found in a fossil state 
in Greece. 
COCCONEIS. 
Cocconeis Grantiana, n. sp., Grev. — Very minute; valve 
elliptic, smooth, with a slender median line and nodule, the 
margin furnished with a moniliform row of large, oblong 
granules. Length -0011". (Fig. 18). 
Hab. On marine shells, Macduff* ; John Grant, Esq. 
A beautiful little object, the smooth disc rendering the 
marginal row of brilliant, bead-like granules more conspicuous. 
Mr. Grant, to whom I am indebted for a specimen, aptly 
compares the entire frustule to a jeweller's ornament set 
with gems. 
