, I0 SYNEDRA. 



S. Vaucherise Kutz. ! (Bac, p. 65, pi. 14, f. 4; H.v.H. Atl., pi. 



40, f. 19* ; Type No. 297), plate 10, fig. 406. 



Valve narrow, linear, with apices attenuate rostrate, pseudo-nodule eccentric ; 



striae robust, 12 or 13 in 1 c.d.m., divided transversely. Length, 3 to 4 

 c.d.m. 



Fresh water. Rouge Cloitre. England (W. Sm., Kitton). Found here and there throughout 

 Europe. 



var. parvula. (S. paroula Kutz. ; H.V.H. Atl., pi. 40, f. 22*), plate 

 10, fig. 407. 



Much smaller, and more lanceolate; striae 14 or 15 in 1 c.d.m- 

 Length, 1*5 to 2 c.d.m. 



var. perminuta Grun. (H.V.H. Atl., pi. 40, f. 23*), plate 10, fig. 

 408. 



Very small (sometimes less than 1 c.d.m.) ; 18 or 19 striae in 1 c.d.m. 



var. deformis. (S. deformis IV. Sm.; H.V.H. Atl., pi. 40, f. 10*), 

 plate 30, fig. 833. 



Valve more or less deformed, with variable distortions; 10 striae in 

 1 c.d.m. 



England (W. Sm., Norman), Scotland (Baxter Coll., No. 2908). 



aa. Valve without a pseudo-nodule, 

 b. VALVES HAVING GENERALLY A MEDIAN HYALINE SPACE. 



S. Ulna (Nitzsch) Ehr. (Inf., p. 211, No. 295, pi. 17, f. 1; 

 H.V.H. Atl., pi. 38, f. 7*; Type No. 284), plate 10, fig. 409. 



Valve narrowly linear, with apices more or less longly rostrate ; pseudo- 

 raphe narrow : stria? robust, 9 in i c.d.m., finely divided transversely, usually 

 leaving a quadrangular hyaline space at the median portion of the valve. 

 Length, about 15 to 25 c.d.m. 



Fresh water. Common. 



var. splendens. (S. splendens Kutz. ; H.V.H. Atl., pi. 38, f. 2*; in 

 Types Nos. 312, 15, 107, etc.), plate 10, fig. 410. 



Much elongated, and attaining as much as 30 c.d.m. in length. 



Fresh water. Common. 



var. subaequalis (Grun.) (H.V.H. Atl., pi. 38, f. 13*; Type No. 

 286), plate 10, fig. 411. 



Valve linear, narrow ; apices obtuse, scarcely or not rostrate-capitate. 



Fresh water. Brussels (Delogne). Rouge Cloitre. 



var. longissima. (S. longissima W. Sm. ; H.V.H. Atl., pi. 38, f. 3* ; 

 Type No. 287), plate 10, fig. 412. 



