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KONGt,. SV. VET. AKADEMIENS HANDLINGAE. BAND 27. N:0 3. 135 



Striae distinctly punctate A. magellanica Pet. 



— not distinctly punctate 4. 



Axial area distinct A. angusta Cl. 



• — — not distinct . . . . . . . . . 5. 



, I Median line straight A. cymhiformis Cl. 



' ' I — — slightly biarcnate ... A. bituminosa Pant. 



1. A. angusta (G-REa. 1857) Cl. — V. narrow, semilanceolate, acute or subacute. L. 0,o4 to 

 0,13; B. 0,005 to 0,0 18 mm. Median line straight, parallel and approximate to the ventral margin. 

 Axial area distinct and frequently moderately broad on the dorsal side, indistinct or small on 

 the ventral side. Strise 7 to 17 in 0,oi mm., not distinctly punctate. Both the dorsal and the 

 ventral sides of the valve are striate. 



This species comprises a number of forms. 



Var. typica Cl. — B. of the frustule 0,oi. L. of the valve 0,05 to OjO.'ss; B. 0,oo5 to 

 0,007 mm. Striae 17 to 18 in 0,oi mm. — A. angusta Greg. D. of Clyde p. 510 PI. XII f. 66. 



A. angusta var. gracilenta Grun. A. S. Atl. XXV f. 15. A. Eulensteinii var. fossiJis Pant. 1889 II 

 p. 36" PL I f. 3, PI. Ill f. 49. Gymhella marina Castr. Chall. Exp. D. p. 31. PI. XXVII f. 13? 



Mai'ine: Scotland (Greg.), Spitsbergen! Sea of Kara! Quincy, Massachusetts! Czekehaza, 

 Hungary (fossil)! Jamaica (Grove Coll.). 



The figure of A. angusta in Diat. of the Clyde is not sufficient for identification without 

 original specimens, but as in the description is stated that it has 17 to 18 striae in 0,oi mm. I 

 think that A. angusta Gres. may denote this form. A. Eulensteinii var. fossilis is described as 

 having 20 to 22,5 striae in 0,oi mm. I found 18 only in specimens from Czekehaza. Gymhella 

 marina Castr. may be this or another form of A. angusta, it is impossible to decide which from 

 the figure and the description. 



Var. oblongella Grun. (1878). — Frustule in breadth 0,oo8 to O.ois. V. in L. 0,o32 to0,068; 



B. 0,006 to 0,01 mm. Striae 14 to 15 in 0,oi mm. — A. oblongella Grun. Casp. Sea D. p. 7 PI. IV 

 f. 20. A. exigua Greg. D. of Clyde p. 514 PL IV f. 75? A. angusta var. arctica Grun. A. D. 

 p. 24 PL I f . 9 (1880). A. lanceolaia var. minor Cl. Vega p. 462 (1883). 



Marine and brackish: Sweden (Bohuslan)! Firth of Tay! East cape! Behrings Island! Ba- 

 learic Islands! Caspian Sea (Grun.), Campeachy Bay! Pensacola! Honolulu! 



A. exigua Greg, may be this form although the strise are stated to be 11 in 0,oi mm., 

 but it is impossible to decide without original specimens. 



Var. Eulensteinii Grun. (1875). — L. of the valve 0,08 to 0,i2i; B. 0,oi6 to 0,02 mm. Strise 

 11 to 12 in 0,0 1 mm. somewhat closer on the ventral side, or about 14 in 0,oi mm. — A. Eulen- 

 steinii A. S. Atl. XXV f. 1 to 3; XL f. 35 to 37. 



Marine: China! Japan! Govans Bay; Raised March; Leton Bank (Atl.), Cape May! 



Var. diducta A. S. (1875). — V. gibbous in the middle. L. 0,o82; B. 0,oi5 mm. Dorsal 

 striae 10 to 11 in 0,oi mm. — A. did. A. S. Atl. XXV f. 13. A. cymhelloides var. latior Grun. 

 Atl. XXV f. 8. 



Marine: Java, Japan (Atl.). 



Var. rentricosa Greg. (1857). — V. in L. 0,05 9 to 0,i3; B. 0,oi3 to 0,oi8 mm. Dorsal striae 

 8 to 9 in 0,01 mm., ventral somewhat closer. — A. ventricosa Greg. D. of Clyde p. 511 PL XII 

 f. 68. A. lanceolata Cl. D. from Spitsb. p. 667 PL XXIII f. 2 (1864). Gymhella criophila Castr. 

 Chall. Exp. D. p. 21 PL XXVII f. 5 1886 (striae distinctly punctate)? Cymiella marina Pant. Ill 

 PL XIX f. 274? 



Marine: Greenland! Spitsbergen! Sea of Kara! Finmark! Coasts of Scotland, Norway and 

 Bohuslan! Adriatic! Bab el Mandeb! Monterey (Atl. XXV f. 6). 



The fig. in Diat. of the Clyde is insufficient for identification, still I have little doubt that 

 Gregory denotes this form. An intermediate form between Var. ventricosa et Var. Eulensteinii 

 is fig. 5 PI XXV in A. S Atl. 



