86 
GrevillEj on New Diatoms. 
Triceratium nebulosum, n. sp.^ Grev. — Valve with concave 
sides and broadly rounded angles^ the ends of which are 
filled with a cloud of minute puncta ; centre occupied with 
an indefinite cluster of small puncta^ while larger ones are 
remotely scattered over the rest of the space. Distance 
between the angles -0032". (Fig. 15.) 
Hab. Barbadoes deposit; exceedingly rare; George Nor- 
man^ Esq. 
This species bears some resemblance in general outline to 
T. trisulcum of Bailey; figured in Pritchard's ' Infusoria/ 4th 
edit.^ pi. viii.^ fig. 27; but there are no transverse lines 
separating the angles from the centre. It is otherwise nearly 
allied to the same diatom^ in the angles being crowded with 
minute puncta and in those of the centre being remotely 
scattered. These latter^ however^ are more numerous than 
in Professor Bailey^s species^ and there is_, besides_, a marginal 
line of irregularly disposed and more closely approximated 
puncta in the concave sides of the valve. It is also allied to 
my T. rotundatum, a much smaller species_, from which it 
difl^ers in the sides being much less deeply concave,, in the 
absence of the single lateral row of large granules^ and in the 
arrangement of the central granules generally. 
Amphiprora. 
Amphiprora conspicua, n. sp., Grev. — Front view broadly 
winged^ much constricted, truncated at the ends ; a row of 
linear nodules at some distance within the margin; strise 
conspicuous, about 18 in -001". Length -0046". (Fig. 16.) 
Hab. Sierra Leone, F. Kitton, Esq. 
The finest species, perhaps, of the whole genus ; allied to 
A. alata, but quite distinct. In the first place, the frustule 
is far from being equally hyaline ; and instead of the strise 
being perceived with some difiiculty, they are rather coarse 
and very conspicuous. Then, in A. alata the number of 
strise (which I have been unable to ascertain satisfactorily for 
myself) is given by Smith as 42 in -001", which is adopted 
by Ralfs in the last edition of Pritchard^s ^ Infusoria ;' but in 
our new species they may be set down at 18 in '001". I 
have found them vary a little, but I assume this number as 
the average. Again, a certain number of the strise swell into 
a sort of linear nodule at some distance within the margin^ 
and the line thus formed, following the marginal curve, con- 
stitutes a most peculiar and striking character. There seems 
to be no fixed rule as to the proportion of strise which exhibit 
