DIATOM A. 



349 



Valves broadly lanceolate or linear, with apices scarcely or not rostrate or 

 capitate. Pseudo-raphe indistinct. Costas delicate, about 5 or 6 in 1 c.d.m. ; 



Fig. 102. 

 Diatoma vul&art. 



stria? fine, delicately punctate, 16 in 1 c.d.m. Girdle face quadrangular, with 

 straight margins. Length, 4 to 5 c.d.m. 



Fresh water. Common throughout Europe. 



van linearis. (H.V.H. Atl., pi. 50 f. 7, 8*), plate it, fig. 466. 



Valve elongate and broadly linear, with apices sometimes somewhat 

 capitate. 



D. elongatum Ag. (Syst., p. 4; h.v.h. Atl., pi. 50, f. 14*, 



18-22*; Type No. 337), plate 11, fig. 467. 



Valve linear, very narrow, with apices more or less capitate. Costa? 



delicate, about 7 in 1 c.d.m. Striae fine, about 17 in 1 c.d.m. Girdle face 

 very narrow, constricted at the median portion. Length, 4 to 7 c.d.m. 



Fresh and brackish water. Throughout Europe, and especially in our latitudes. 



var. tenue. (). tenue Ag. ; H.V.H. Atl., pi. 50. f. 14a and i>* ; in 

 Type No. 337), plate 11, fig. 468. 



