Greville,, on New Diatoms. 
95 
Amphora. 
Amphora Sarniensis, n. sp._, Grev. — Frustules sharply 
constricted at the middle; lobes with a double undulation, 
the ends produced, truncate ; striae about 30 in -001". Length 
•0017" to -0022". (Fig. 12.) 
Hab. Guernsey; Dr„ Wallich. 
A beautiful and most distinct little species, with an outline 
reminding the observer of some species of Euastrum. It is 
readily distinguished from all other species of the section 
characterised by a distinct middle constriction, by possessing 
two undulations between the nodule and the extremities. 
The first is large, from which the margin descends in a more 
or less sharp curve, and then forms a sort of shoulder, before 
the frustule contracts into the short, broadly linear, produced 
ends. It is a very hyaline species, but the striae are evident 
at the margin, although very obscure in the middle of the 
frustule. As will be seen by the figures, there is some varia- 
tion in the relative proportions, some being less deeply con- 
stricted, the undulations less prominent, and the breadth 
greater or less in proportion to the length. I have given the 
extreme range of variation which has come under my notice. 
Navicula. 
Navicula indicaj n. sp., Grev. — Large, broadly elliptical, 
with mammseform ends; striae fine, about 30 in '001", form- 
ing a narrow marginal band ; similar striae forming a linear 
band on each side the median line, next to which is a linear 
blank space, the rest of the interior being filled up with a 
minute equal granulation. Length '0043' . (Fig. 13.) 
Hab. Ceylon; Dr. Macrae. 
A beautiful Navicula, having the form of N. clavata, but 
no real affinity with that species. The very fine striae consti- 
tute a marginal band, considerably less than a third of the 
space between the margin and the median line, and also a 
very narrow linear band on each side of the median line, 
which, like the median line itself, is interrupted at the central 
nodule. The whole of the internal area is filled up with a 
minute uniform granulation, except a narrow blank line, 
which occurs on the median boundary, and which becomes 
attenuated and disappears near the ends. In some respects, 
this fine diatom is allied to N. prceteojta, but diff'ers in im- 
portant particulars. The striae in the latter are bold and 
moniliform, and there are no definite striated bands next the 
median line, as in our new species. The granulation in 
