312 



SYNEDRA 



Valve narrowly lanceolate, with apices slightly rostrate-capitate ; pseudo- 

 raphe narrow; strioe well marked, about 13 in 1 c.d.m., interrupted in the 

 middle of the valve by a hyaline space, elongated, generally quadrangular. 

 Length, about 13 c.d.m. 



Freshwater. Brussels (Delogne) England (W. Sm., Comber). Ireland (O'Meara). Here 

 and there throughout Europe. 



var. delicatissima Grun. (S. deluatissima W. Sm. ; H.V.H. Atl., 

 pi. 39, f. 7* ; in Types Nos. 221, 269, etc.), plate 10, fig. 421. 



Shorter and much narrower, with apices somewhat more strongly 

 capitate ; striae extending throughout the valve. Length, 5 to 10 c.d.m. 



Freshwater. Antwerp, Brussels, etc. England (Kitton, Norman). Ireland (O'Meara). 



var. angustissima Grun. (H.V.H. Atl., pi. 39, f. 10*), plate 10, 

 fig. 422. 



Very long, with median portion somewhat inflated, apices excessively 

 narrow, feebly capitate. Length, 20 c.d.m. 



Fresh water. 



S. radians (Kutz.) Grun. (h.v.h. Atl., pi. 39, f. ti ; Type No. 



289 and in Types Nos. 221 and 312), plate 10, fig. 423. 



Valve very narrowly linear, lanceolate, with apices somewhat capitate ; 

 striae fine, 16 to 17-5 in 1 c.d.m. Length, 4 to 10 c.d.m. 



Fresh water. Rouge Cloltre (Del. ), Ard Lieg. (De Wild.). Antwerp (H.V.H.). England 

 (Kitton, Comber, Norman). Scotland. Ireland (O'Meara), 



bb. STRI.E NOT LEAVING A HYALINE SPACE IN THE MEDIAN PORTION OF THE VALVE. 



c. Valves with apices not capitate, sometimes somewhat rostrate. Marine species. 



S. Gallionii Ehr. (inf., p. 212, pi. 17, f. 2; h.v.h. Atl., pi. 39^ 



f. 18* ; Type No. 291 and Type No. 292 var.), plate 10, fig. 424. 



Valve linear lanceolate, with apices rounded, sub-obtuse. Pseudo-raphe 

 very distinct, somewhat enlarged at the median portion ; terminal nodules very 

 distinct. Striae robust, about 9 in 1 c.d.m., distinctly punctate, absent at the 

 apices of the v.ilve, which are covered with very fine granules. Length, 16 to 

 22 c.d.m. 



Marine. -Not yet found in Belgium. England (W. Sm., Stolt), Scotland (Kitton in Baxter 

 Coll. No. 4293), Ireland (O'Meara), and on all the Coasts of Europe. 



