113 
tate, radiate and interrupted at the central nodule by a stauronei- 
form blank space not reaching the margin of the valve. 
ffab.—Fresh water. In streams, Clifton, frequent though 
not abundant. (Plate LXIX., fig. 10.) 
This species has been placed in the genus Stauronezs by Kiitz- 
ing, on account of the peculiar shortening of the striz opposite 
the central nodule ; it is, however, a genuine Vavicula.— Donkin. 
NAVICULA LONGA, Greg. 
Navicula longa, Ralfs in Prit. Infus., p. 906 ; Donkin, Brit. Diat., p. 55, pl. 
VIIL., figs. 3a and 3b; O’Meara, Rep. on Irish Diat., p. 344, 345, p!. 30, fig. 11. 
Valve lanceolate, narrow ; coste stout, radiate, shorter oppo- 
_ site the central nodule. 
Hab.—Marine. South Beach on submerged timber. (Plate 
LXIX., fig. 11.) 
NAVICULA RECTANGULATA, Greg. 
Navicula rectangulata, Greg., Diat. of the Clyde, p. 7, pl. L, fig. 7; Ralfs in 
Prit. Infus., p. 907; Donkin, Brit. Diat., p. 66, pl. X., fig. 5; O’Meara, Rep. on 
Trish Diat., p. 343, pl. 30, fig. 8. j 
Pinnularia rectangulata, Rabenh., p. 215. 
Valve linear, with broadly rounded ends, bulging at the mid- 
dle ; intermediate free space narrow, but roundly inflated in the 
middle ; costz stout, converging opposite the inflated space and 
radiate towards the extremities. 
Hab.—Marine. South Beach. (Plate LXIX., fig. 12.) 
NAVICULA MAJOR; Kutz. 
Navicula major, Kutz., Bacill., p. 97, t. IV., figs. 19 and 20; Ralfs in Prit. 
Infus., p. 896, pl. VII., fig. 65; Donkin, Brit. Diat., p. 69, pl. XI., figs. 2a and 2b; 
Van Heurck, Syn. Diat. Belg., pl. V., figs. 3 and 4; Schum., Diat. der Hohen 
Tatra, p. 70. 
Pinnularia major, Rabenh., Sussw. Diat., p. 42, t. VL, fig. 5; Sm., Syn., Vol. 
i., p. 54, pl. XVIIL, fig. 162; Brun., Diat. Alpes and Jura, p. 84, pl. VIII., fig. 1. 
Valve broad, linear, distended in the middle and at the 
rounded extremities; intermediate free space broad; central 
nodule large and round; coste stout, convergent opposite cen- 
tral nodule and slightly eadiate towards the extremities. 
Hab.—F resh water, frequent. (Plate LXIX., fig. 13.) 
This species scarcely differs from WV. nobilis and N. gigas, 
oe by its somewhat smaller size and closer pinnules.—a//s. 
NAVICULA LIMoSA, Kiitz. 
Navicula limosa, Kuiz., Bacill., p. tor, t. TIL, fig.50; Rabenh., Sussw. Diat., | 
