130 
GrevillEj on New Diatoms. 
Hah. Red Sea; cabinet of Laurence Hardman, Esq. 
The intermediate linear band of striae serves to distinguish 
this species at a glance. It has at first sight the appearance 
of a cleft in the valve, for the striae, being very fine, are not at 
once perceived. It extends generally to about two thirds of 
the length of the valve. Sometimes it follows the curve of 
the valve, but in others (as in the figure) it is straight or very 
nearly so. 
Navicula excavata, n. sp., Grev. — Elliptic, with an external 
band of fine striae, less than half the semi-diameter of the 
valve in breadth, and a very narrow series next the median 
line ; intermediate space obscurely cellulate, with a large 
sudden indentation opposite the nodule. Length about '0030''. 
(Fig. 15.) 
Hah. Red Sea ; cabinet of Laurence Hardman, Esq. 
A species having much of the contour of N. Hennedyi, but 
differing from it in the much finer striae (about 35 in -QOr^) 
and in the large remarkable notch or excavation in the inter- 
mediate space opposite the nodule into which the marginal 
striae extend. 
