38 NAVICULE. 
2. Valve sublinear, with a median sinuous constriction. 
Navicula incurva, Gregory. 
Navicula ncurva, Greg. Quart. Micr. Journ. vol. iv. p. 8, pl. i. fig. 26; 
Ralfs, in Prit. Inf. p. 893; Rabenh. Europ. Diat. p. 203. 
Navicula? Biblarium?, Ehren. Mikrogeo. t. XVII. i. figs. 8 & 9? 
Plate VI. fig. 2. 
Frustule small. V. hyaline, oblong, with incurved mar- 
gins, and produced, broad, subcapitate extremities ; 
striz obscure. 
Hab. Fresh water. River Findhorn, Loch Leven, Scot- 
land (Prof. Gregory). 
Navicula binodis, Ehrenberg. 
Navicula binodis, Ehren. Abh. Berl. 1840, p. 18; Kiitz. Bac. p.100, t, iii. 
fig. 35; Rabenh. Stissw. Diat. p. 41, t. v. fig. 5, and Europ. 
Diat. p. 203; Sm. Synop. vol. i. p. 53, pl. xvii. fig. 159; Ralfs, 
in Prit. Inf. p. 893. 
Fragillaria? binodis, Ehren. Amer, 1843, p, 127, 
Plate VI. fig. 3. 
Frustule minute. V. oblong, divided into two suborbicular 
lobes by a median sinuous constriction; extremities 
produced, narrow, nearly linear, obtuse ; strize obscure. 
Hab. Fresh water: frequent. 
8. Valve lanceolate. 
Navicula rhynchocephala, Kiitzing. 
Navicula rhynchocephala, Kiitz. Bac. t. xxx. fig. 85; Sm. Synop. vol. i. 
p. 47, pl. xvi. fig. 182; Ralfs, in Prit. Inf. p. 900, pl. vii. 
