NAVICULA LITTORALIS. 5 
Section I. Vatve BROAD, FLATTENED. 
Subsection I. Valve elliptical or oval ; strice interrupted. 
A. Extremities rounded ; strie reaching to the median line, but crossed 
or interrupted on each side of it by a longitudinal line, or two lines, 
extending between the apices of the valve. 
Navicula hyalina, Donkin. 
Navicula hyalina, Donk. Quart. Micr. Journ. vol. i. n. 8. p.10, pl. i. fig. 6 ; 
Rabenh. Europ. Diat. p. 181. 
Plate I. fig. 1. 
V. linear-elliptical ; strize very fine, indistinct or obsolete ; 
median line broad, tapering towards the central and 
terminal nodules, and bordered on either side by a 
doubly incurved longitudinal line; terminal nodules 
elongated, narrow. 
The hyaline valve with striz so delicate that they can 
be resolved only with extreme difficulty, even in dry 
specimens, together with the peculiar elongated, terminal 
nodules, appearing as if inserted into a cleft of the median 
line, are characters sufficiently distinguishing this species. 
Hab. Marine. Coast of Northumberland, on the sands 
between tide-marks, at Cresswell and Boulmar. 
Navicula littoralis, Donkin, n. sp. 
Plate I. fig. 2. 
V. oval; strize slightly inclined, close, very fine, distinct, 
and crossed near to their inner ends by a straight lon- 
gitudinal line, nearly parallel with the median line; 
dry valve yellowish brown. 
This species is closely allied to N. estiva, but readily 
