KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 27. N:0 3. 103 



This little form scarcely belongs to A. ovalis and is remarkable for the strongly striate 

 dorsal and ventral sides, as well as for the absence of central area. Perhaps a small form of 

 the following. A. Froteus var. parvula Flögel Pommerania Exp. p. 89 f. 10 may represent 

 this form. 



7. A. marina (W. Sm. 1857?) V. H. (1880). — Frustule in outline elliptical or orbicular, 

 with truncate ends. L. 0, 04; B. 0, 025 mm. V. luneate, with subacnte ends and slightly eoncave 

 ventral margin. L. 0,04 to 0,o6; B. 0,oi to 0,oi3 mm. Median line slightly biarcnate. Axial and 

 central areas not distinct on the dorsal side. Strife 15 in 0, 01 ram. coarsely punctate, not inter- 

 rupted or crossed by a longiti^dinal line. Ventral side narrow, striate as the dorsal side. — 

 A. N. H. 1857 p. 7 Pl. I f. 2? V. H. Syn. p. 58 Pl. I f. 16. A. S. Atl. XXVII f. 14, 17, 18. 

 A. pelhicida Greg. D. of Clyde p. 513 Pl. XII f. 73? A. vana Flögel Pommerania Exp. p. 90 f. 12? 



Marine: North Sea! Baleainc Islands! Seychelles! China! Porto Seguro (Deby Ooll.)! 



A. marina of AV. Sm. is too badly figured for Identification. According to Arnott (M. J. 

 VI p. 206) A. marina is identical with A. Proteufi of G-reg., but if so the strise are incorrectly 

 stated as 40 in 0,ooi". A. ^jeUurida Greg. is too imperfectlj^ described and figured for admitting 

 of identification, but it seems to be the same as A. .marina. A. marina is doubtful as a species, 

 probably a form of A. Protens. 



8. A. Protens Greg. (1857). — Frustule elliptical with truncate ends, about twice as long 

 as broad. Valve Innate, obtuse. L. 0, 04 to 0,o6 5; B. 0, 005 to 0,oi6 mm. Median line biarcnate. 

 Axial area indistinct on the dorsal side. No central area. Strise on the dorsal side 9 to 13 in 

 0,01 mm. not interrupted and coarsely punctate. Ventral side striate, especially towards the ends. 

 Strioe radiate, approximate to the median line and crossed by a narrow, blank band. — D. of Clyde 

 p. 518 Pl. XIII f. 81. A. S. Atl. XXVII f. 3. A. Prot. var. Kariana Grun. A. I), p. 24 Pl. I 

 f. 7 (1880). A. hexagonalis O. Witt Mus. Godeffroi I p. 66 Pl. VIII f. 12? A. speciosa Castr. 

 Voyage Challenger p. 17 Pl. XXVII t 1? 



Marine: Greenland! Spitsbergen! Finmark! Sea of Kära! Cape Deschneff! North Sea! S:t 

 Helena! Campeachy Bay! Mediterranean Sea! Black Sea! Seychelles! China! Galapagos Islands! 



Var. contigua Cl. — Strite on the ventral side not crossed by a blank, narrow band. — 

 A. S. Atl. XXVII f. 7 to 9. Probably also XXVIII f. 4. 



Marine: North Sea! Adriatic! Labuan! New Caledonia! 



Var. alata Cl. — V. L. 0,13; B. 0,032 mm. Dorsal side with a projecting hyaline limbus 

 in the middle. Striee 12 in 0,oi mm. 



Marine: Baltjic Dept. (Van Heurck CoU.)! 



9. A. robusta Greg. (1857). — Frustule in outline broadly elliptical, with truncate ends. 

 L. 0,065 to 0,17; B. 0,038 to 0,12 mm. Valve lunate with arcuate dorsal margin and straight 

 ventral margin. Median line strongly biarcnate. Axial and central area indistinct on the dorsal 

 side. Dorsal side with strong strife, 6 to 7 in 0, 01 mm, not crossed by a longitndinal line, 

 coarsely punctate; puncta about 8 in 0,oi mm. Ventral side broad, with a more or less broad 

 band of coarse radiate strite along the median line. — D. of Clyde p. 516 Pl. XIII f. 79. 



Mai'ine: Spitsbergen (strife 10 in 0,oi mm.)! North Sea! Mediterranean Sea! Adriatic! Ma- 

 cassar Straits! Japan (fossil)! Samoa! 



Var. fusca Cl. — Conneeting zone with a number of small, irregular puncta, giving it a 

 brownish colour. L. 0,12; B. 0,o7 5 mm. Striis 6 in 0,oi mm. 



Marine: China (Deby CoU.)! 



Var. subplicata Cl. — Conneeting zone with traces of longitudinal divisions and longitndinal 

 rows of puncta. L. 0,115; B. 0,04 5 mm. Strise 8 in 0,oi mm. 



Marine: S:ta Monica, Cal. fossil (Deby Coll.)! 



