428 DIATOMACEJS. 



species of the genus Cymbella : JV. amphora Ehr., N. lineolata 

 Ehr., and N. JVestermanni. 



1. CYMBELLA ZEBRA Hass. 

 Plate C. Fig. 8. 



Char. Frustules in side view semi-lanceolate, truncate ; in 

 front aspect elongated, quadrangular, with straight sides. 

 Striae distant, strongly marked, double. 



Navicula zebra, Abhandl. der Akademie d. Wissensch. zu 

 Berlin, p. 262. ; Bericht. der Akademie d. Wissensch. 

 zu Berlin, 1837, p. 53. Eunotia zebra Ehr., Die 

 Infus. p. 191. pi. xiv. fig. 7. pi. xxi. f. 19. 



Hab. Cheshunt : A. H. H. On the moist conglomerate 

 sandstone cones near Cushendall, co. Antrim : Mr. 

 Moore. 



This fine species approaches rather closely to the following, 

 from which it differs however in two respects ; in the stria;, 

 which in Eunotia zebra are less numerous than in E. turgida, 

 and in the form of the frustule, which in the front view is 

 not attenuated at the extremities as it is in that species. 



2. CYMBELLA TURGIDA Hass. 

 Plate C. Fig. 7. 



Char. Frustules semi-lanceolate , truncate at either extremity 

 in side view ; in lateral aspect narrower towards either 

 end than in the centre. 



Navicula turgida, Abhandl. der Akademie d. Wissensch. 

 zu Berlin, 1830. Eunotia turgida, Bericht. der Aka- 

 demie d. Wissensch. zu Berlin, 1837, p. 45. ; Die Infus. 

 p. 190. t. xiv. fig. 5. 



Hab. Storrington Common : Mr. Jenner. 



This species needs only to be contrasted with Cymbella 

 zebra, from which it differs in the two particulars indicated 

 in the description of that species, viz. in its finer and closer 



