228 GREVILLE, ON NEW DIATOMS. 
closely allied to the Monterey specimens, having the peculiar 
glistening nodules, Nitzschoid form, and marginal puncta. 
In these the intimate structure is more visible; the pale 
puncta distinctly radiating from the centre, and becoming 
decussate towards the ends. There can be no doubt, I 
think, that the three diatoms constitute a very natural genus. 
As I have been unable to ascertain positively whether the 
valves of the Barbadoes species are keeled (although I be- 
lieve them to be so), I have inserted this character doubt- 
fully. It will be perceived that I have framed the generic 
character on the assumption that this little group belongs, 
with Nitzschia, to the Fragilariee, and that the figures con- 
sequently represent the front view. But it must be confessed 
that, for a front view, the appearance is not a little strange. 
Rutilaria Epsilon (Kitton), n. sp., Grev.—Frustule lanceo- 
late, with linear, elongated, obtuse apices; nodule very 
large, with three conspicuous convolutions. Length ‘0080’. 
(BIMEX, fie, 15) 
Nitzschia Epsilon, Kitton, in litt. 
Hab. Monterey deposit; F. Kitton, Esq., C. Johnson, 
Esq., R. K. G. 
Frustules transparent, minutely and faintly punctate, the 
puncta forming decussating lines ; margin with a row of dark, 
conspicuous puncta. Central nodule very glistening, large, 
occupying the greater part of the diameter of the frustule, 
composed of a semilunate body, with the horns, as it were, 
convolute, and having secondary horns arising out of and 
a little to the exterior of the others, also more or less conyo- 
lute. A few large scattered puncta are generally present on 
each side of the nodule. Although there are no terminal 
nodules, there is sometimes the appearance of them, owing, 
apparently, to some peculiarity of structure influencing the 
transmission of light at the apices. The most remarkable 
feature in this diatom is the nodule, which, as a rule, is 
symmetrical, but here it is the reverse, and so whimsical in 
its configuration that 1t may be compared to some old- 
fashioned drawer-handle represented in alto-relievo. 
Rutilaria ventricosa, n. sp., Grev.—Frustules ventricose, 
with short, linear extremities; nodule circular, nodulose ; 
puncta radiating, decussate towards the ends. Length about 
70040". (Fig. 2.) 
Hab. Barbadoes deposit, from Cambridge estate; C. 
Johnson, Esq., R. K. G. 
A much smaller species than the preceding, and relatively 
shorter, but not unlike it in general form. The nodule, 
however, is quite different, being circular, with some ap- 
