!3 2 



AMPHORA. 



5. Halamphora CI. Longitudinal lines absent. Ventral portion 

 of the valve narrow. Valve with apices generally capitate and 

 recurved. Beads distinctly arranged in transverse striae and in series 

 of longitudinal undulations. 



f Fr 



0. 

 E 

 o 



f Striae with puncta some- 

 what indistinct, very 

 delicate 



a 

 c 



to J 





ANALYSIS OF SPECIES. 



istules complex, beads resolving into a mass of fine puncta ..... 

 f Frustules with external margins undulated ....... 



Transverse strire almost invisible, longitudinal conspicuous 

 Transverse strire fine, median more robust 

 f Sutural zone abruptly dilated at the apices 



1 Sutural ( Frustule elliptic, with sutural zone lanceolate 



I zone not < 



I dilated. ( Frustule suboval, with apices rostrate-capitate 



f Frustules 

 more or less 

 constricted - 



r 



Strire 



with 



distinct 



puncta. 



Frustules 

 robust. 



Frustules 

 delicate. 



in the mid- 

 dle. 



Constriction slight, frustule broad, sutural zone with numerous 

 folds ........ 



I L I 



Frustules 

 not con- 

 stricted. 



Constriction considerable, frustule narrow, sutural zone without 

 folds ........ 



Connecting zone with very numerous folds 



Puncta robust, frustule rostrate-capitate 



Sutural 

 zone not -J 

 plicate. 



A. Eunotia. 

 A. Sarniensis. 



A. coffeaeformis. 

 A. veneta. 

 A. commutata. 

 A. cymbifera. 

 A. rostrata. 



A. angularis. 



A. binodis. 



A. inflexa. 

 A. turgida. 



Puncta 

 delicate or 

 resolvable - 



with 

 difficulty. 



f Transverse strire conspic- 

 uous, about 9 in 1 

 c.d.m. ; frustule very 

 long, about 8-9 c.d.m. A. Ergadensis. 



Ranhe I Striae conspicuous, about 

 straight "' I2 ' n l c -^ m - > frustule 



short, about 5 c.d.m. . A. macilenta. 



! Strire . delicate, finely 

 punctate, about 13-14 

 in 1 c.d.m. ; frustule 

 short, about 5 c.d.m. . A. acutiuscula. 



Raphe curved, frustule very short, 

 about 3 5 c.d.m. ; striae very deli- 

 cate, about 19 in 1 c.d.m. . . A. salina. 



A. commutata Grun. ! (A. affinis W. Sm. S.B.D. L, p. 19, pi. 



2, f. 27, not Kutz ! W. Sm. prep. No. 27 ! H.V.H. Atl., pi. i.,f. 14* ; Type 

 No. 7) plate 1, fig. 13. 



Frustule oblong with rounded or truncate apices ; connecting zone abruptly 

 inflated towards the apex, marked with several fine longitudinal striae. 

 Valves with dorsal margin straight at median part, then abruptly attenuate and 

 forming an obtuse point in consequence of a corresponding constriction in the 

 ventral margin ; raphe strongly inflexed ; striae, robust on dorsal side, 9 in 1 

 c.d.m. ; fine and marginal on ventral side, 15 in 1 c.d.m. Length, 5 to 6 c.d.m. 



Brackish waters Antwerp, Blankenberghe, Heyst, Ostend (H.V.H.) ; England (W. Sm ! 

 Stolterfoth.) ; Scotland (Greg); France; Germany! Norway! and probably throughout the 

 shores of the North Sea, 



\ 



