KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 26. N:0 2. 15 



Var. Fohornyana Grun. (18(>0). — Frustule slightly coiistricted. L. 0,u6 5 toU.us?; B. 0, 02 to 

 0,02 7 mm. Juiiction-line sliglitly sinuose. Valve narrow, linear, with rostrate ends, and almost 

 straight median line. — Grun. Verh. 1860 p. ,i69 Pl. VI f. 9. 



Brackisli water: Neusiedlersee (Hungary); Sea of Kära (Grun.). 



The above description is from the work of Grunow. In Cl. M. D. N:o 256 (Lymington, 

 England) occiirs a form, determined by Grunow as A. Pokorn. L. 0, 09; B. 0, 04 mm. Strite 

 16 in 0,01 mm., coarsely punctate on the keel. Junction-line slightly sinnose. Keel strongly 

 sigmoid. 



Var. punctiilata Grun. (1880). — Frustule slightly constricted. L. 0,0.37 to 0,095 mm. B. 0,02 

 to 0,023 mm. Junction-line not sinuose, with a row of small puncta. Striae about 27, on the keel 

 24 in 0,01 mm. — A. pal. v. pund. Grun. A. I), p. 62, Pl. IV f. 84. Franz Josephs L. D. p. 53 

 (105), Pl. I f. 54, 55. 



Brackish water: Sea of Kära! Franz Josephs Land (Grun.), Cape Wankarema! 



Var. Nereis Lewis (1861). — Frustule strongly constricted in the middle. L. 0, 05 to 0,i 14 mm 

 Junction-line not sinuose, but with distant puncta. Strige 22 in 0, 01 mm. V. narrow, lanceolate, 

 with sigmoid median line. — A. Ncrels Lewis. Proc. Acad. N. Se. Philadelphia 1861 p. 64. — 

 A. plicata var. japonica Castr. Challenger Exp. 1). p. 40, Pl. XXX, f. 8. 



Marine: Atlantic coasts of N. America (Lewis). 



Var. dilatata Pant. (1891). — Frustule strongly constricted. L. 0, 139. Height of the valve 

 0,025; at the constriction 0,oi05 mm. Junction-line crenulated. Striise 25 in O.oi mm. — A. dila- 

 tata Pant. II. p. 55, Pl. X f. 179. 



Brackish water: Hungary, fossil (Pant.). 



This form only differs from var. Nereis by its somewhat larger size. 



Var. horeaJis Grun. (1880). — Frustule slightly constricted. L. 0, 079 to O, oss; B. 0, 028 to 

 0,03 mm. Junction-line slightly arcuate, not sinuose. Stripe on the keel 23, on the valve and the 

 connecting zone 26 in 0, 01 mm. — A. pal. var.? borealis Grun. A. D. p. 62, Pl. IV f. 85. 



Brackish water: Sea of Kära (Grun.), Cape Wankarema! 



Var. duplex Donk. (1858). — Frustule in L. 0,02 to 0,o66; B. 0,oi to 0, 04 mm. Junction-line 

 arcuate, not sinuose. Strite very fine. V. narrow, lanceolate, with strongly sigmoid median line. 

 — A. dupl. DoNK. T. M. S. VI p. 29, Pl. III f. 13. — A. pal. v. dupl. V. H. Syn. p. 121, Pl. 

 XXII f. 15, 16. 



Brackish water: Greenland! North Sea (Sweden! England, Donk., Belgium V. H.) Hungary, 

 fossil (Pant.). 



Var. hynlina Eulenst. (1880). — As Var. duplex but smaller. L. 0,017; B. O, oss mm. — 

 A. hyalina Eul. in V. H. Syn. Pl. XXII f. 17. 



Brackish water: Cette (Grun.). 



A. ]}alndosa is a very variable species, closely connected with A. alafa. Nearly akin to 

 A. pahidosa, perhaps a variety, is A. Kiltzingiana Grev. (1863 Edinb. N. Ph. J. XVIII p. 184 

 f. 6) from Queensland. The frustule is deeply constricted. L. O, i2s mm. The jimction-line is 

 not sinuose. 



2. A. Diiseiiii Cl. N. Sp. — Frustule membranaceous, strongly constricted in the middle, 

 the segments being almost orbicnlar. L. 0,13; B. 0,ii at the constr. 0, 07 mm. Zone with sigmoid 

 longitudinal divisions, 2 in 0, 01 mm., finely striate; striee 17 in 0, 01 mm. V. strongly compressed 

 and elevated, without any junction-line. Strite (at the keel) 12 in 0, 01 mm., curved, towards the 

 keel with di.stant puncta, 8 in 0, 01 mm. 



Brackish water (mouths of rivers): Cameroon (Dusen)! 



3. A. iilata KtiTZ (1844). — Frustule strongly silicious, constricted in the middle. B. 0, 04. 

 Junction-line not sinuose, but frequently with a row of large puncta. V. linear, with acuminate 

 ends. L. 0, 10 to O, n; B. 0,02 mm. Median line strongly sigmoid. Basis of the keel linear, sigmoid. 



