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 FlOgbl 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. O.oas mm. V. luneate, with subacute ends and slightly concave 

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

 central areas not distinct on the dorsal side. Strise 15 in 0,oi mm. coarsely punctate, not inter- 

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

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

 A. pellucida Greg. D. of Clyde p. 513 PL XII f. 73? A. nana Flogel Pommerania Exp. p. 90 f. 12? 



Marine: North Sea! Balearic Islands! Seychelles! China! Porto Seguro (Deby Coll.)! 



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

 VI p. 206) A. marina is identical with A. Proteus of Greg., but if so the strise are incorrectly 

 stated as 40 in 0,ooi". A. pellucida Greg, is too imperfectly 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. Proteus. 



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

 as broad. Valve lunate, obtuse. L. 0,04 to 0,065; B. 0,oo5 to 0,oi6 mm. Median line biarcuate. 

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

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

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

 p. 518 PL Xin f. 81. A. S. Atl. XXVII f 3. A. Frot. var. Kariana Geun. A. D. p. 24 PL I 

 f. 7 (1880). A. hexagonalis 0. Witt Mus. Godeffroi I p. 66 PL VIII f. 12? A. speciosa Castr. 

 Voyage Challenger p. 17 PL XXVII i. 1? 



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

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



Var. contigua Cl. — Strise 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,i3; B. 0,032" mm. Dorsal side with a projecting hyaline limbus 

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



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



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

 L: 0,06 5 to 0,17; B. 0,0 38 to 0,i2 mm. Valve lunate with arcuate dorsaL margin and straight 

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

 side. Dorsal side with strong strise, 6 to 7 in 0,oi mm, not crossed by a longitudinal line, 

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

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



Marine: Spitsbergen (strise 10 in 0,oi mm.)! North Sea! Mediterranean Sea! Adriatic! Ma- 

 cassar Straits! Japan (fossil)! Samoa! 



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

 brownish colour. L. 0,12; B. 0,07 5 mm. Strise 6 in 0,oi mm. 



Marine: China (Deby Coll.)! 



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

 rows of puncta. L. 0,115; B. 0,045 mm. Strise 8 in 0,oi mm. 



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



