22 NAVICULE ®. 
and flattened ; striz oblique, reaching to the median 
line, distinct, much coarser and more distant opposite 
the central nodule. 
Hab. Fresh water. Lough Mourne deposit. 
Navicula Gastrum, Ehrenberg. 
Pinnularia Gastrum, Ehren. Amer. p. 183, t. TIT. vii. fig. 22, and Mi- 
krogeo. t. V. i. fig. 12, t. XV. A. fig. 23; Rabenh. Siissw. Diat, 
p. 44, t. vi. fig. 15. 
Navicula Gastrum, Kiitz. Bac. p. 94, t. xxviii. fig. 56; Ralfs, in Prit. 
Inf. p. 900. 
Navicula varians, Greg. Trans. Micr. Soc. vol. iii. n. s. p.10, pl. ii. figs. 
ry 
sii Plate III. fig. 10. 
Frustule small. V. broad, elliptical, slightly constricted 
into broad flattened extremities ; strize coarse, costate, 
reaching to the median line, oblique and parallel, 
except opposite the central nodule, where they are 
transverse, shortened, and of unequal length. 
Ehrenberg’s figure in the ‘ Mikrogeologie,’ of this species 
as it occurs in the Loch-Mourne deposit, is very charac- 
teristic. The figure in the present work also represents a 
specimen from the same deposit. It is easily recognized 
from N. Semen by the great difference in the character of 
its striz in the middle of the valve. 
Hab. Fresh water. Loch-Mourne deposit (A. S. D.); 
Scotland (Prof. Gregory). 
Navicula cocconeiformis, Gregory. 
Navicula cocconeifornus, Greg. Quart. Micr. Journ. vol. iv. p. 6, pl i. 
fig. 22; Grev. Ann. & Mag. Nat. Hist. 2nd ser. vol. xv. pl. ix. 
fig. 6; Sm. Synop. vol. ii. p. 92; Ralfs, in Prit. Inf. p. 896; 
Rabenh. Europ. Diat. pp. 186 & 189. 
Plate IIL, fig. 11, 
Frustule small. V. broad, elliptical, and slightly con- 
