KONGL. SV. VET. AKADEMIENS IIANDLINGAl?. RANI) 27. N:o 3. 129 



side very narrow. Its striae 15 in 0,01 mm. ■ Hedwigia VI p. 23. M. J. 1877 p. 178 PI. CXCV 

 f. 9. A. D. p. 2.5. Icon. n. PI. IV f. 10. 



Marine: Balearic Islands! Adriatic! China! Honduras ((ilrnn.), Barbados! 



Var. hriocensis Lbud. Fortm. Ms. — Frustule elliptical, with truncate ends. L. 0,045; 

 B. 0,02 mm. Zone with about S divisions in 0,oi mm. ti-ansversely striate; stria; 1") in 0,(ii mm. 

 Dorsal oblique stria; 21 in O.oi mm. — PL IV f. 11. 



Marine: The Eng. Channel (Deby Coll.)! 



13. A. Lunula Cl. N. Sp. — V. lunate, with subacute ends and straight ventral margin. 

 L. 0,1. •J to 0,15; B. 0,0 18 to 0,02 mm. Median line straight, not very closely approximate to the 

 ventral margin. Central nodule transversely dilated into a stauros. StilcB on the dorsal side 

 almost parallel, 14 to 17 in 0,oi mm., composed of distinct puncta, about 13 in O.oi mm. Ventral 

 side striate; stricP 12 to 15 in 0,oi mm. punctate. — ■ PI. IV f. 13. 



Marine: Balearic Islands! Sumatra (Deby Coll.)! Colon (Deby Coll.)! 



14. A. staurophora (Castr. 188G?) Cl. — Frustule hyaline, in outline quadrate to rec- 

 tangular. V. slightly indented in the middle of the dorsal margin, narrow, with obtuse ends. 

 L. O.o.') to 0,0.-)-); B. 0.01 mm. Median line straight, at some distance from the ventral margin. 

 Central nodule dilated to a tran.sverse stauros. StrisB delicate, punctate, about 20 iii 0,oi mm. — 

 A. sp. A. S. Atl. XXV f. 85, 86. A. stam-ophom Castr. Voyage Challenger p. 20 PI. XXVII f. (i? 

 Icon. n. PI. IV f. 33, 34. 



Marine: Davis Straits (Atl.), North Sea (Atl.), Morocco! Balearic Islands! Pensacola! 

 This form is only imperfectly known and requires further investigations. 



15. A. ostrearia Breb. (1849). — Frustule silicious, in outline elliptical to quadrate, or 

 rectangular. Zone with numerous divisions, 3 to 9 in 0,oi mm., distinctly striate. V. of varioiis 

 apparent shapes, depending on its positions. L. 0,0.3 to 0,17; B. 0,005 to 0,o2 mm. Median line 

 biarcuate. Central nodule transversely dilated to a stauros. Dorsal and ventral side with about 

 e(juinumerous, distinctly punctate stria;, 10 to 17 in 0,oi mm. 



A. osfrearia is very variable in size and in the number of stria'. The valves have very 

 different shapes in diiferent positions, and for these reasons a large number of forms have been, 

 often in a very incomplete manner, described or figured as distinct species. 



Var. vifrm Cl. (1868). — L. of frustule 0,o8g to 0,i; B. 0,o68 mm. Zone with 4 to 5 divi- 

 sions in 0,01 mm. its strife 10 to 11 in 0,oi mm. Stria; on the dorsal and ventral side 9 to 10 

 in 0,01 mm. composed of puncta, about 10 in 0,oi mm. — A. ritrca Cl. Svenska och N. D. p. 237 

 PI. IV f. 5. A. S. Atl. XXVI f. 25. .4. Nora Caledonica Grun. A. S. Atl. XXVI f. \i\ (1875). 

 A. Forcf'Uus Kitton A. S. Atl. XXXIX f. 15 to 17. A. Trcuhii Leud. Fortm. D. de la Malaisie 

 p. 11 PI. I f. 7 (1892)? 



Marine: Spitsbergen! Bohuslan ! Mediterranean Sea! Labuan! Japan (Atl.), New Caledonia 

 (Atl.), West Indies! 



Var. fypica V,h. — Frustule 0,o.3r. to 0,o8 mm. in length and 0,02 to 0,o6 mm. in breadth. 

 Zone with 3 to 5 divisions in 0,oi mm. Its strite about 13 in 0,oi mm. StricE of the valve 11 

 to 13 in 0,01 mm.; their puncta about 12 in 0,oi mm. — A. ostrearia KfiTz Sp. Alg. p. 94. Grun. 



A. D. p. 25. A. S. Atl. XXVI f. 23. V. H. Syn. p. 55 PL I f. 25. A. mvnihranacm W. Sm. 



B. D. I p. 20 PL II f. 29 1853 (strite are stated to be 31 in 0,oi mm., but are distinct on the 

 figure at an enlargement of 400 only). A. quadrata Br^b. Kiltz Sp. Alg. p. 95 (1849)? A. elegans 

 Greg. T. M. S. V p. 70 PL I f. 30 (1857)? A. liforalis Doxk. T. M. S. VI p. 30 PL III f. 15 

 (1858). A. Fctitii Temp, and Brun D. foss. du Japon p. 15 PL IX f. 16 (1889). A. Nova Caledo- 

 trirr, Pant. Ill PL XV f. 227 (1893). 



Marine: Finmark! North Sea! Mediteri-anean Sea! Sumatra! Labuan! China (Deby Coll.)! 

 .lapan (Brun. Coll.)! 



K. Sv. Vet. Akad. Hiuidl. BbikI 21. N:o 3. 17 



