Greville^ on New Diatoms, 
85 
constricted^ with ovate-cuneate lobes,, minutely punctate ; 
margin composed of a single series of large, linear-oblong 
cellules, which, as well as the puncta, disappear opposite the 
central nodule. Length -0050''. (Fig. 29. 
Hab. Zanzibar ; Professor Hamilton. L. Smith. 
One of the most exquisite diatoms which have ever come 
under my observatio.^, and for which I am indebted to the 
kindness of my excellent correspondent, Professor H. L. 
Smith, Gambler, Ohio, who is prosecuting original and im- 
portant investigations into the structure and development of 
the diatom frustule. The present new species belongs to the 
extensive group of NaviculcB, in wliich the valves are more 
or less constricted at the middle, constituting the exploded 
genus Diploneis of Ehrenberg. Its nearest ally appears to be 
N. margiJiata^ of Lewis,""^ in which there is also a minute 
inner structure, and a single row of large marginal cellules. 
In N. spectalissimay however, this contrast of structure is 
carried much farther, for the puncta next the median line are 
more minute, and the marginal cellules form a band nearly as 
broad as the punctate portion itself. These cellules are 7 in 
'001'', and at the widest part of the valve are '0004'' in length, 
and so regular as to give the margin a pectinate and crenate 
character. They gradually diminish in length, and disappear 
near the apex, and opposite the central nodule. 
Stauroneis. 
Stauroneis rotwidata, n. sp., Grev. — Small ; valve linear, 
or very slightly dilated in the middle, rounded at the ends ; 
stauros broad, linear, reaching to the margin ; striae parallel, 
exceedingly fine, not quite reaching to the median line. 
Length -0033". (Figs. 30, 31.) 
St. rotundata ; Grev. MS.; Dr. L. Lindsay. ^Journ. 
Linn. Soc.,^ vol. ix, p. 134 (name only). 
Hab. Otago, in New Zealand, in fresh water ; Dr. 
Lauder Lindsay. 
This seems a well-marked species, with its parallel sides 
(sometimes slightly dilated at the middle) and very rounded 
ends, where the margin is broader than at the sides. 
Staw'oneis scapJiulcefoymis, n. sp., Grev. — Small; valve 
linear ; lanceolate somewhat contracted and produced at the 
sub-acute ends, which are arched over by the thickened 
* ' Notes on new and larer species of Diatomaceas of the United States' 
seaboard.' By 1\ W. Lewis, M.D., 18G1, p. 6, pi. ii, lig-. 1. 
