KONGL, SV. VET, AKADEMIENS HANDLINGAR. BAND. 27. N:0 3. 



117 



32. A. margaritifera Cl. N. Sp. — Frustule indented in the middle, bicuneate, with broad, 

 truncate ends. L. 0,027 to 0,04; B. 0,oi5 mm. Zone with about 4 divisions in 0,oi mm. coarsely 

 transversely striate. Striae 8 in 0,oi mm., composed of distinct puncta. V. with arcuate dorsal, 

 slightly convex ventral margin, and rostrate ends. L. 0,o35; B. 0,oi mm. Median line straight. 

 Longitudinal line indistinct. Central nodule not stauroid. Axial area indistinct; central small 

 rounded. Dorsal strise 8 in 0,oi mm., composed of a few large puncta, crossed by a broad, blank 

 area. Ventral side with a row of small puncta along the margin (10 to 11 in 0,oi mm.). — 

 PI. Ill f. 30, 31. 



Marine: Galapagos Islands! 



Subgenus Halamphora Cl. 



Frustule elongated, sometimes constricted in the middle. Connecting zone complex. Valve 

 boat-shaped, usually with rostrate or capitate ends. Median line close to the ventral margin. 

 Axial area usually indistinct. No longitudinal line on the dorsal or ventral side. Structure: 

 puncta disposed in transverse strise. 



This subgenus, to which belongs A. salina of W. Smith, comprises a large number of 

 forms, closely connected in part. They differ from Cymbamphora by the zone being complex, by 

 the, usually, capitate ends and the distinctly punctate strifB. The small terrestrial A. Normani 

 seems to be related to A. perpusilla of the subgenus Amphora, so also A. veneta and A. commu- 

 tata, otherwise there is no close connection between this and any other group of Amphora. 



■■{ 



5. - 



Artificial key. 



Striae crossed by a longitudinal band . . 



— — by several — blank lines . 



— not — — — .... 

 Striae with distant puncta 



— closely punctate . . 

 Dorsal margip slightly triundulate 



— — not undulate . 

 Valve constricted 



— not — ■ . 

 Valve with one constriction 



- two constrictions 



— — several — ... 

 Zone on the dorsal side reticulate . 



- — — not — 

 Constriction with a median gibbosity 



without — — 



{Divisions of the zone faint . . 

 — — — distinct 



i Dorsal strise about 13 in 0,oi mm. 

 I _ _ 9 to 10 ^ — . 



{Undulations equal . 

 Median undulation larger than the others . 



... ( Strise 5 in 0,oi mm 



( — 9 to 10 in 0,01 mm 



I Ends of the valve not capitate 



\ — — — capitate, i)ot curved inwards 



J Ends not rostrate .... . . , 



I — rostrate, curved inwards . 



_( StrisB 20 in 0,oi mm .' 



■ I — 12 to 14 in 0,01 mm , . 



'1' 



8, 



9. 



10, 



12 



14 



. . . A. inter secta A. S. 

 . A. czekehazensis Pant. 

 2. 

 3. 

 . . 4. 



A. Grunowii A. S. 

 A. corpulenta Cl. a.- Grove. 



. . 5. 



. . . . .11. 



. . .6. 

 . A. Jeschkei Jan. 

 . . . . 10. 

 . A. Peragalli Cl. 

 . . 7. 

 . A. bullata Cl. 



A. bigibba Gbun. 



. . .9. 



A. trinodis Gbbg. 



A. angularis Gkeg. 



A. tetragibba Cl. 



A. sarniensis Gbev. 



. A. clara A. S. 



13. 



, . 13. 



. 18. 



. . 14. 



16. 



. A. veneta KOtz. 



15. 



