Fig. 1. 
> 
N@ gr 
PLATE IV. 
NavicuLa ELEGANS, Smith. 
. Navicuza supsatina, Donkin. 
NavicuLaA PALPEBRALIS, De Brébisson. a, the 
typical form; 4, var. in which the median blank 
space is lanceolate, and the striee opposite the 
central nodule slightly shortened. 
NavicuLa aANGULOosA, Gregory. 
NavicuLa sEMIPLENA, Greville. 
NavicuLa alpina, Smith. a,8.V.; 6, M.V. 
NavicuLa LatiuscuLa, Kiitzing. 
