3 2 4 



FRAGILARIA. 



F. undata W. Sm. (S.B.D., ii., p. 24, pi. 60, f. 377*), plate 



30, fig. 841. 



Valves elliptic or longly oval, with apices acuminate and more or less 

 rostrate. Stria? delicate, 17 in 1 c.d.m. Filaments separating easily, and 

 frustules then cohering by their angles. Length, 2 to 5 c.d.m. 



Fresh water. England (W. Sm.), Lock Kinnord Dep. Scotland (Davidson), 



var. constricta. Valves constricted at the median portion. 



Fresh water. Scotland (Mull Dep. W. Sm.), 



F. Striatula Lyngb. (Hydroph. Dan., p. 183, pi. 63A; H.V.H. 

 Atl., pi. 45, f. 12*), plate 30, fig. 842. 



Valve narrowly lanceolate, with apices somewhat attenuate. Pseudo-raphe 

 very narrow. Striae very delicate, 24 in 1 c.d.m. Frustules quadrangular, 

 elongated, with connecting zone plicate, in long filaments, very easily deformed, 

 imperfectly silicious. 



Marine. England, Scotland, Ireland, France (probably Belgium), Germany, Norway. 



F. hyalina (Kiitz.) Grun. {Diaioma hyalina Kiitz., Baa, p. 47, 

 pi. 17. f. 20 ; H.V.H. Atl., pi. 44, f. 14 and 15* ; Type No. 310), plate ir, 

 fig- 443- 



Valve linear, narrow, hyaline, with apices feebly inflated, terminal nodules 

 distinct; striae very fine, scarcely visible, 31 or 32 in 1 c.d.m. Girdle face 

 quadrangular, elongated, with apices rounded, sometimes inflated, connecting 

 zone showing numerous fine longitudinal striae. Length, 45 to 7*5 c.d.m. 



Marine. Not yet found in Belgium. England, Ireland. 



F. Crotonensis (A. M. Edwards) Kitton. ! (Science Gossip, 

 1869, p. no, f. 81*), plate 11, fig. 444. 



Valve linear, very narrow, slightly inflated at the median portion, with 

 apices capitate; striae 15 in 1- c.d.m. Girdle face strongly inflated at the 

 median portion, and slightly enlarged at the apices. Frustules united in 

 filaments at the middle. Length, 4 to n c.d.m. 



Fresh water. Town ditches at Antwerp (only once observed). Ireland (O'Meara). 



