NAVICULA. I 73 



N. subcapitata Greg. (Q.J. M.S. 1856, p. 9, pi. 1, f. 30, h.v.h. 

 Atl., pi. 6, f. 22*), plate 2, fig. 91. 



Valve very narrow, linear, somewhat attenuated at the median portion, with 

 apices rostrate, gently sub-capitate; costae rather distant, about u to 12 in 1 

 c.d.m., not reaching to the raphe, and absent in the middle of the valve ; 

 terminal nodules rather large. Length about 2*5 to 3*5 c.d.m. 



Freshwater. Noire-fontaine (Delogne) ; Manage (P. Gaut.) ; England, Ireland. 



Var. paucistriata. (H.V.H. Atl., pi. 6, f. 23*), plate 2, fig. 92. 



Striae short, diminishing gradually in length, and absent on all the 

 median portion of the valve. 



N. appendiculata Kutz. (Baa, p. 93, pi. 3, f. 18; pi. 4, f. 



1, 2; pi. 5, f. 5 ; H.V.H. Atl., pi. 6, f. iS and 20*), plate 2, fig. 93. 



Valve narrow, linear, very feebly attenuate at the median portion, with 

 apices feebly rostrate-subcapitate ; costae delicate, 16 or 17 in 1 c.d.m., 

 not reaching to the raphe, radiate at the median portion of the valve, 

 where they are gradually shortened, so as to leave a large stauronei- 

 form hyaline space, convergent at the apices. Length, 2*5 to 3*5 

 c.d.m. 



Fresh water. Brussels Botanical Gardens (Del.). Found throughout Europe. 

 bb. Valves considerably inflated at the median portion . 



N. globiceps Greg.! (Q.j.m.s. 1856, iv., p. 10, pi. r, f. 34; 



H.V.H. Atl. Supp., f. 13* in Type No. 284), plate 2, fig. 94. 



Small, linear-oblong, inflated at the median portion with apices broadly 

 rostrate-capitate. Costae not reaching to the raphe, leaving a large 

 hyaline space round the central nodule, 16 to 18 in 1 c.d.m.; the 

 median ones very radiate, the terminal convergent ; central nodule large. 

 Length, 3 to 4 c.d.m. 



Fresh water. Rare. Antwerp in the Schyn, etc. Canal d' Herenthals. Scotland (Greg !). 



N. Braunii Grun. ! H.V.H. Atl., pi. 6, f. 21*), plate 2, 



fig- 95- 



Linear-lanceolate, with apices to an average degree rostrate-capitate. 

 Costae not reaching to the raphe, 10 or 11 in 1 c.d.m.; the median ones 

 strongly radiate, the terminal convergent, gradually shortened up to nearly 

 the middle of the valve, where they leave a broad stauroneiform hyaline 

 space; central nodule narrow. Length, 4 c.d.m. 



Fresh water. Liresse (Delogne). 



