CYLINDROTHECA. 



409 



Tribe XVlII.Cylindrothecece. 



GENUS 83. CYLINDROTHECA RABH, 



1859. 



Frustules fusiform, furnished with 2 or 3 lines 

 (carinae?), arranged spirally, and showing juxta- 

 posed (carinal ?) dots. 



One species. 



C. gracilis (Br e b.) Grun. ! {Ceratoneis 



Breb. ; Nitzschia Ticnia, IV. Sm. ; Cyhndrotheca 

 Gerstenbergeri Rab. ; H.V.H. Atl., pi. 80, f. 2*; Type 

 No. 417), plate 17, fig. 574. 



Frustule becoming abruptly fusiform ; spiral line 

 with 20 to 22 elongated dots in 1 c.d.m. Length, 

 about 7 to 8 c.d.m. 



Freshwater. Brussels (Delogne). Antwerp (H.V.H. ), England 

 (Ralfs, W. Sm., Comber, Stolt., Norman). 



Fig. 132. 

 Cylindrotheca gracilis. 



