1 86 NAVICULA. 



the apex of the valve, 4 or 5 in 1 c.d.m., leaving a small hyaline area round 

 the central nodule. Length, 10 to 20 c.d.m. Breadth, about 1*5 c.d.m. 



Marine. England, Scotland, Ireland, Denmark, Jutland. 



N. Solaris Greg. (T.M.S., 1856, iv., p. 43, pi. 5, f. 10*), plate 25, 

 fig. 717. 



Valve elongate, narrowly lanceolate, with very obtuse apices. Striae 14 to 

 16 in 1 c.d.m., radiate up to the apices of the valve, resting rather distant from 

 the raphe and leaving a considerable hyaline area round the central nodule. 

 Length, 6 to 12 c.d.m. Breadth, 1 to 1-5 c.d.m. 



Marine England, Scotland, Ireland, Denmark. 



N. lanceolata Kutz. ! (Baa, p. 94 , pi. 30, f. 48 ; h.v.h. Ati, 

 pi. 8, f. 16*; Type No. 96), plate 3, fig. 139. 



Valve lanceolate, with apices gently diminuate-rostrate ; striae shortened 

 round the central nodule, radiate up to the apices of the valve, about 12 in 

 1 c.d.m. in the middle of the valve; 15 to 16 at the apices. Length, about 

 3 to 5 c.d.m. Breadth, about 1 c.d.m. 



Fresh water Between Louvain and Parck (P.G.), Ard. Lieg (De Wild.). Throughout Europe. 



forma curta. (H.V.H. Atl., pi. 7, f. 17*), plate 3, fig. 140. 



Mixed with the preceding. 



var. phyllepta. (AT. phyllepta Kutz; H.V.H. Atl., pi. 8, f. 40*; 

 Type No. 100), plate 3, fig. 141. 



Smaller than the type form, with stria? more delicale and much more 

 compact, about 18 in 1 c.d.m. 



Brackish water Blankenberghe. 



var. arenaria. (N. arenaria Donk., H.V.H. Atl., pi. 8, f. 18*; 

 Type No. 97), plate 3, fig. 142. 



Much larger and more gradually attenuate than the type form. About 

 10 stria? in 1 c.d.m. 



Marine Not yet found in Belgium. England (Donkin), Ireland (O'Meara), Scotland. 



N. Gastrum (Ehr.) Donk. (Br. Diat., p. 22, pi. 3, f. 10; 



H.V.H. Atl., pi. 8, f. 25, 27 and 32*), plate 3, fig. 134. 



Valve broadly elliptic with obtuse apices, broadly rounded, very gently 

 constricted-subrostrate. Central nodule surrounded by a hyaline area, rounded 

 or elongated transversely. Striae surrounding the nodule, alternately long and 

 short. Striae finely divided transversely, radiate up to the apex of the valve, 



