2T2 NAVIGULA. 



N. Scandinavica (Lag.) Ad. Schm. (sub Stauroneis in Salltv. 



Bohuslan, p. 47 ; Ad. Schm. Nordsee, pi. 1, f. 29*), plate 27, fig. 764. 



Valve lanceolate, with apices produced-subrostrate. Striae radiant, reaching 

 to the raphe, about 10 to 11*5 in 1 c.d.m., with strong puncta, shortened near 

 the central nodule, where they leave a stauroneiform space, narrow, elongate. 

 Length, 6-5 to 10-5 c.d.m. Breadth, 3 to 3-5 c.d.m. 



Marine. Bahusie (Lag.). North Sea (Ad. Schm.). 



Note. Most authors have confounded this species with N. lacustris Greg. 

 According to authentic specimens of Gregory in our possession, N. lacustris is 

 a form almost typical of N. Placentula Ehr. (Syn., pi. 8, f. 28). 



N. Baileyana Grun. (in Ad. Schm. Atl., pi. 6, f. 26*; N.granu- 



lata Bail, nee Breb.), plate 27, fig. 765. 



Valve elliptic or elliptic oval ; striae strongly granular, about 8 in 1 c.d.m. 

 with approximate granules at the margin of the valve, but becoming scattered 

 as they approach the raphe. Raphe sometimes enlarged and accompanied 

 by a hyaline area, equally enlarged on each side of the valve. Central 

 nodule elongated, surrounded by a stauroneiform hyaline area, more or 

 less elongate, narrow. Length, 5 to 8 c.d.m. Breadth, 2-5 to 3*5 c.d.m. 



Marine. North Sea (Hvidingsoe, Ad. Schm. ; Bahusie CI.). 



N. fraudulenta Ad. Schm. (in Atl, pi. 70, f. 60*), plate 27, 



fig. 766. 



Valve regularly elliptic ; stria; not reaching to the raphe, 10 in i c.d.m. 

 at the middle of the valve, somewhat radiant, formed of rather strong 

 granules, distant, leaving a small hyaline area round the central nodule. 

 Length, about 3 c.d.m. Breadth, almost 2 c.d.m. 



Marine. North Sea (Solsvig, Ad. Schm.). 



N. marina Ralfs. (in Pritch. inf., p. 9 o 3 ; h.v.h. Atl., pi. n, 



f. 16*; Type No. 118), plate 4, fig. 184. 



Valve broadly oval, with sub-acute apices. Raphe surrounded by a 

 narrow irregular hyaline zone, somewhat enlarged round the central nodule. 

 Stria; radiate, 10 or 11 in 1 c.d.m., formed of very coarse puncta. Length, 

 6 to 7 c.d.m. Breadth, 2-5 to 3-5 c.d.m. 



Marine? (Brackish water, according to Donkin). Very rare : Washings of mussels (Debv). 

 England, Ireland, France. 



