14 NAVICULE.E. 
2. Extremities produced. 
Navicula Lyra, Ehrenberg. 
Navicula Lyra, Ehren. Amer. 1848, p. 131, t. I. i. fig. 9a; Ktitz. Bac. 
p. 94, t. xxvili. fig. 55; Spec. Alo. p. 74; Sm. Synop. vol. ii. 
p. 93; Greg. Diat. of the Clyde, p. 13, pl. i. fig. 18; Ralfs, in 
Prit. Inf. p. 897; Rabenh. Europ. Diat. p. 177. 
Navicula Gregoriania, Grev. Quart. Micr. Journ. vol. v. p. 10, pl. ili. 
fig. 7. 
Plate II. fig. 7. 
V. linear, elliptical, with produced broad rounded extre- 
mities, or linear with cuneate or subcuneate extremi- 
ties ; striz granular, 22 to 24 in ‘001"; marginal band 
wide, and broadest in the middle; unstriated area 
narrow, linear, strongly incurved in the middle and 
everted towards the extremities, which reach to or 
near the margin of the valve. 
In this species the marginal band of strize is proportion- 
ately wider than in the other members of the present 
group; it is further distinguished by the double lyre-shaped 
blank space on the surface of the valve. 
In the variety with cuneate apices, and in short stunted 
specimens generally, the longitudinal unstriated areas are 
frequently straight instead of everted towards their unde- 
veloped extremities, which do not reach to the margin of 
the valve. 
Hab. Marine. Salt Pans, Hampshire (Prof. Smith) ; 
Cumbrae (Dr. Walker Arnott); Isle of Arran and Loch 
Fyne (Prof. Gregory); Flamboro’ Head (Mr. Norman) ; 
on the sandy beach, Northumberland, in several localities, 
abundant (A. S. D.). 
