293 
spring at Ingram, on the river Breamish, mixed with a 
sprinkling of S. biseriata. 
3. Surirella tenera, Gregory. Quart. Jour. Micr. Sci./ 
Yol. IV, p. 11, PI. I, 38.) 
Frustule on F. V. elongated, narrow, cuneate. Valve on 
S. V. elongated, narrow, ovate; plicfe transverse, slightly 
inclined near the extremities, conspicuous, reaching to the 
median line, semi-cvlindrical ; the inner narrow, about 8 
in 001". 
Allied to S. splendida, but a very much smaller and more 
slender species, and.with much finer plicse. 
This form was described by Professor Gregory as a doubt- 
ful species, being under the impression that it might be the 
perfectly developed S. linearis. After ample investigation, 
however, I feel satisfied that it is a distinct and well-marked 
species. 
Hab. Fresh water. River Coquet, Elyhaugh, May, 1869, 
frequent. Banffshire, Professor Gregory. 
4. Navicula Coquedensis, Donkin. 
Very large. Valve on S. V. broad, oblong, much inflated 
in the middle ; extremities broad, rotund, slightly dilated ; 
striae moniliform, connivent, sub-distant from the median 
line, gradually shortened around the centre, and absent from 
the extremities ; about 30 in •001" subdividing dichotomously 
opposite the centre. 
Hab. Fresh water. River Coquet, Elyhaugh, May, 1869. 
5. Navicula vernalis, Donkin. 
Syn. — A'. varians, Greg., ‘ Trans. Micr. Soc.,’ vol. iii, p. 12, pi. 
ii, 14, 15, 25. 
Valve short, broad, elliptical, or slightly lanceolate, with 
broad, rotund extremities ; striae reaching to the median line, 
distant, robust, obliquely inclined towards the centre ; oppo- 
site the centre more distant, direct, much shorter, and of 
unequal length, so as to leave an irregularly triangular blank 
space on either side of the centre. 
This well-marked species appears to have been first detected 
by the late Professor Gregory in a gathering from Dudding- 
stone Loch, in 1853, and placed by him in a numerous group 
of forms, which he referred to an undescribed species or type 
which he named N. varians. 1 This group undoubtedly con- 
1 * Trans. Micr. Soc.,’ vol. iii, p. 10, pi. ii. 
