NAVICULA MAJOR. 69 
Navicula gentilis, Donkin, n. sp. 
Navicula major, var. b. crassa, Bréb. in Rabenh. Alg. n. 683; Europ. 
Diat, p. 210? 
Plate XII. fig. 1. 
Frustule large, elongated. V. linear, slightly bulging in 
the middle and expanding towards the broadly rounded 
clavate extremities; stricee not reaching to the median 
line, strongly costate and obliquely inclined towards 
the central and terminal nodules, 18 in :001". 
This species is quite distinct from N. nobilis, which 
it resembles, being very much smaller, proportionally 
broader at the extremities, and having much finer striz. 
Nevertheless it appears to have been confounded with the 
latter species and with N. major. 
Hab. Fresh water: frequent. In hilly districts: Che- 
viots, Northumberland ; Lough-Mourne deposit, &c. 
Navicula major, Kiitzing. 
Navicula major, Kiitz. Bac. p. 97, t. iv. figs. 19 & 20; Ralfs, in Prit. 
Inf. p. 896, pl. vii. fig. 65. 
Bacillaria fulva, Nitzsch (ex parte), t. ii. figs. 13 & 17, 1817. 
Frustulia major, Kiitz. Syn. p. 19, fig. 25, 1838. 
Navicula viridis, Ehren. in Pogg. Ann. 1836, t. iii, fig. 1, Inf. 1838, 
t. xiii. fig. 16, t. xxi. fig. 12; Baily, in Amer. Journ. Jan, 1832, 
pl. ii. figs. 16 & 17. 
Pinnularia viridis, Ehren. Amer. 1848, t. I. i. fig. 7, iii. fig. 3, iv. fig. 3, 
t. II. i. fig. 22, iii. fig. 1, v. fig. 2, vi. fig. 21, t. TIL. i. figs. 1 & 2. 
Pinnularia major, Rabenh, Siissw. Diat. p. 42, t. vi. fig. 5, Alg. n. 621 
& 1485, and Europ. Diat. p. 210; Sm. Synop. vol. i. p. 54, 
pl. xviii. fig. 162. 
Plate XI. figs. 2a & 20. 
Frustule large, elongated. V. broadly linear, turgid in 
the middle; extremities gently and gradually round- 
ed; striz not reaching to the median line, strongly 
H 
