SYSTEMATIC ACCOUNT 343 



The puncta are almost square, slightly rounded towards the centre, becoming smaller 

 as they approach the margin where they become clusters of very fine puncta. Apical 

 axis of cell 28-64/x ; transapical axis 16-40/x. 



A typical neritic diatom, common around the European coasts. It was observed at 

 one station only on the 30th W meridian, at a considerable distance from land, in the 

 company, however, of several other species which are not true inhabitants of the 

 plankton. 



Observed at St. 670. 



Suborder BIRAPHIDINEAE 



Family NAVICULACEAE 



Subfamily NAVICULOIDEAE 



1. Cells isobilateral upon apical and transapical axis. Valves flat or nearly so, striation monili- 

 form, usually slightly radiate, valve structure simple ... ... ... ... ... Navicula 



2. Valve structure laminate ... ... ... ... ... ... ... ... ... Trachyneis 



3. Axile area raised, striae moniliform, transverse, not reaching valve margin, forming lateral 

 hyaline areas ... ... ... ... ... ... ... ... ... ... Scoresbya 



4. Cells in valve view sigmoid, striation very fine... ... ... ... ... Pleurosigma 



Subfamily AMPHIPROROIDEAE 



1. Cells with alate projections, median line sigmoid, zone complex ... ... Amphiprora 



2. Median line straight, zone simple ... ... ... ... ... ... Tropidoneis 



Subfamily NAVICULOIDEAE 



Genus Navicula Bory 

 Bory, 1822 b, p. 128 



As there have been many conflicting statements in the literature concerning the date 

 of the first publication of the genus Navicula, the following note is not without interest. 

 The genus was described first by Bory de Saint Vincent in the Dictionnaire Classique 

 D'Histoire Naturelle, vol. 11, p. 128, under Bacillariees, p. 127. Bory described the genus 

 and stated that " Le Vibrio tripunctatus de Muller est le type de ce genre." Reference 

 was also made to a figure (fig. 3). The plates of vol. xvn of the Dictionnaire were published 

 in fascicules of ten plates, but no indication was given of the dates of publication. 

 Plate 54 bears the illustration referred to in fig. 3. The illustration was very small, and 

 apart from representing a boat-shaped organism it would be impossible to make any 

 specific determination of it. Three species of Navicula were illustrated, N. unipunctata, 

 N. bipunctata, N. tripunctata. The epithets referred to the large rounded dots which 

 appeared in the organism. From the position and size of these dots I consider them to 

 represent cell contents and not markings upon the valve surface. Ehrenberg in In- 

 fusionsthierchen (1838) placed these species as doubtful synonyms under Navicula 

 gracilis. 



D XVI 25 



