126 



AMPHORA. 



Analysis of Groups. 



Puncta rather coarse, very distinct, forming transverse 

 strife and undulating longitudinal lines . 



Connecting -[ 

 zone not 

 plicate 



Connecting 

 zone plicate 



Puncta 

 not 



forming 

 longitu- 

 dinal 

 lines 



Ventral portion of valve broad, stria; finely 

 punctate on both parts of the valve 



Ventral portion of valve very narrow, strife 

 not distinctly beaded 



Coarse puncta, very distinct, arranged in straight trans- 

 verse and longitudinal lines .... 



f Valve with ventral portion narrow, apices 

 generally rostrate-capitate and recurved, 

 beads forming undulating longitudinal 

 lines ...... 



Valve with central port'on smooth, 

 furnished with a longitudinal 

 ridge .... 



1 



Puncta 

 not 



forming 

 straight { 

 ongitu- 

 dinal 

 lines 



Not 



as 



above 



Ventral 

 portion 

 striate. 



Ventral portion rather 

 broad, the two parts 

 with identical stria- 

 tion, raphe with bran- 

 ches divergent from 

 the central nodule . 



Ventral portion very 

 narrow, with finer 

 striation than that of 

 the dorsal portion ; 

 raphe straight, near 

 the margin ; central 

 nodule often stauro- 

 form . 



Subg. i. 

 Amphora. 



Subg. 2. 

 Psaniinamphora 



Subg. 3. 



Cyrnbampliora. 



Subg. 4. 

 Diplamphora. 



Subg. 5. 

 Halamphora. 



Subg. 6. 

 Calampliora. 



Subg. 7. 

 Amblyamphora. 



Subg. 8. 

 Oxyamphora. 



A. Sutural zone not plicate. 



GROUP i. Amphora Ventral and dorsal portions of the valve 

 generally furnished with a longitudinal line (a rib or narrow 

 area). Beads rather coarse, forming at the same time transverse 

 striae and undulating longitudinal lines. (Type: A. ovalis). 



Non- 

 marine 



Marine 

 forms 



ANALYSIS OF SPECIES. 



f Fresh water ; striae robust in the type form ; pseudo-stauros very 

 distinct ........ 



:orms. Humid places (walls, etc.) 



Raphe slightly incurved, 

 stauros 



spurious 



Frustule not 

 subrectangu- 

 lar, apices 

 obtuse or 

 truncate 



t. Raphe concave, no spurious stauros 



Striae fine, resolvable 



A. ovalis 



A. Normanii. 

 A. perpmilla. 



A. marina. 

 A. Fusio. 



14 to 16 striae 



in 1 c.d.m. . I Striae strong, irresolvable 



/ Raphe with ventral portion com- 

 About 10 striae J P^ely striated . . A. robusta. 



in 1 c.d.m. . | Raphe with ventral portion 

 I, v having only some lines of dots A. Proteus. 



Frustule with acute or subacute apices, dorsal margin of valve 

 plicate longitudinally . . . . . .A. dubia. 



Frustule subquadrangular, striae extending throughout the ventral 



portion of the valve . . . . . . .A. arenicola. 



