18 
Greville,, on New Diatoms. 
blank space. In the New Zealand frustules it is very con- 
siderably smaller. 
Navicula notabilis, n. sp._, Grev. — Valve oval^ with extra- 
median lines_, and near them a parallel uninterrupted line of 
minute granules on each side^ and with a band of marginal 
granules^ composed of three or four longitudinal contiguous 
series^ the intermediate wide blank space obscurely striated. 
Length -0020" to -0030". (Fig. 9.) 
Hab. Cook^s Reef, Torres Straits j G. Norman, Esq. 
A singularly rich and delicate species, totally distinct from 
all that I am acquainted with. The whole valve seems to be 
made up of microscopic strings of beads. Even the extra- 
median lines which run close to the true median line are 
very minutely punctate. Then comes another straight line 
of fine granules on each side, scarcely more distant from the 
extra-median lines than they are from each other, not con- 
tracted in the slightest degree opposite the central nodule, 
and converging just before reaching the ends. Between 
these lines and the margin the space is divided into two 
equal parts, the one being blank, or at least only obscurely 
transversely striated, the other filled up with about four rows 
of granules, following the curve of the margin. The two 
inner of these rows are distinctly defined ; the others are more 
or less confluent. The only variation I have observed is in 
size and in the tendency of the smaller specimens to approach 
a circular form. 
Navicula luxuriosa, n. sp., Grev. — Valve elliptical, some- 
what obtuse; striae composed of distinct oblong puncta, so 
arranged as to form longitudinal lines contracted opposite 
the nodule; the margin, as well as an intra- marginal line or 
ridge, also' composed of close puncta. Length '0030'' to 
•0038." (Figs. 10, 11.) 
Hab, Port Stephen, New South Wales, in a dredging com- 
municated by Dr. E/ol3erts. 
It is utterly impossible for the pencil to convey any idea of 
the exceeding beauty of this little object. Under a mode- 
rately magnifying power the delicate striation is scarcely 
perceived; but the intra-marginal line at once strikes the 
eye, as well as the indication of wavy longitudinal lines. 
Under a higher power the surface of the valve is seen to be 
undulated ; the intra-marginal line, especially, forming a pro- 
minent ridge, leaving a sort of channel between it and the 
margin. The median is accompanied by parallel extra- 
median lines, straight at the sides and converging towarJs 
the ends. Then follow three longitudinal, convex lines of 
puncta, contracted opposite the nodule, at which point they 
