KdNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 26. NIO 2. 43 



the eiids. Central area rather large, irregularly rhuiuboid. Traiisv. and obl. strite "/,-, '7isi "/n, 

 i9/ig, "/i9 ill 0,0 1 mm. — F. qiiadratum var.? rhomheum Grun. A. D. p. 50. F. rhomb. Per. Ill 

 f. 13, U. 



Marilie: Java! Labuan! Port Jackson! Aukland (Grun.), Öamoa! Cliina! Oakland, California! 



F. rhomheum greatly resembles F. quadratvm and angulafutn, but differs by the more ex- 

 centrio median line and tlie coarser striation. 



36. P. obscunim W. Sji. (1852). — V. narrow linear, witli nuilaterally narrowed and 

 rounded ends. L. 0,09 to O, i.i; B. 0,oi mm. Median line strongly as^^mmetrical, near the ends 

 close to the curved margin. Transv. and obl. strite eqnidistant, 25 (Per.) to 29 (W. Sm.) in 0,ui 

 mm. — W. Sm. Ann. M. Nat. H. [2] IX p. 8 Pl. 1 f. 11. B. D. I p. 65 Pl. XX f. 206. Per. I 

 f. 14, 15. F. macilentum Per. p. 13, Pl. V f. 24 (1891). 



Marine: England (W . Sm.), Balearic Islands (Per.). 



Var. barbadeiisis Cl. L. O, 14 to O.is; B. 0,oi5 ram. Transv. and obl. stri» 'Y.,^, -"/ji 



in 0,01 mm. 



Marine: Barbados! • 



.w. ,...,.. 



37. P. (Rhoicosigma) faleatuiu Douk. (1861). — V. linear, witb imilaterally narrowed and 



roiinded ends. L. O, is to O, is; B. 0,oi5 mm. Median line Hexnose in tlie middle, strongly ex- 

 centric, foUowing the cnrved margins of the ends. Strite fine, obliqne. — Donk. M. J. I p. 7 Pl. I 

 f. 1. Bhoic. falcaf. Grcx. Hedw. VI p. 20 (1867). Per. IX f. 25, 27. 



Marine : Northumberland (Donk.). 



Doubtful; specimens iu Grove's coUection are Gyroaigina arcticuni Cl. 



38. P. (Rhoicosigma?) iiicertiim Per. (l.sgi). — V. slender, sigmoid, acute. L. 0,.33; B. 

 0,0 19 mm. Median line sliglitly sinuose, very excentric towards the ends. Transv. and obl. strite 

 "'/,7 in 0,0 1 mm. - Per. p. 32 Pl. IX f. 21. 



Marine: Atlantic coast of North America! 



39. P. (Rhoicosigma) Wcissflogii Grun. (1880). — V. linear, witli unilaterallj^ narrowed 

 and ronnded ends. L. 0,ii8 to 0, 1.34; B. O.ois to O,oi'.i mm. Median line excentric, and strongly 

 sigmoid, closely following tlie curved margins for a considerable distance. Median oblique strite 

 cross each other in an angle of 90°; the terminal more acute. Transv. and obl. stri;« -'/ji in 0, 01 

 mm. - EJioic. Weissfl. Grun. A. D. p. 54. Per. IX f. 23, 24. 



Marine: Seychelles (V. H. coU.)! 



40. P. umhilicatnm Cl. N. Sp. — V. linear, with unilaterally rounded and very slightly 

 rostrate ends. L. 0,o6.t to (',10; B. 0, 01.') mm. Median line strongly sigmoid, for a long distance 

 closely following the convex margin of the valve. Central area unusually large, transverse and 

 rounded. Transv. and obl. strite eqnidistant, 22 in O.oi mm. — Pl. IV f. 22. 



Marine : Labuan ! 



This species is in form nearest to F. Weissflogii, but differs by the large area, tiiid tlie 

 close striation. 



41. P. E.xsul (!l. N. Sp. — V. linear-lanceolate, gently sigmoid, with subacute ends. L. O, is; 

 B. 0,0 18 mm. Median line strongly sigmoid and excentric, enclosed between two longitudinal lines. 

 Central nodule small, rounded. Transv. and obl. stritB --/is in 0,oi mm. — Pl. IV f. 17. 



Marine: Gulf of Naples (Deby CoU.)! 



This species, of which I have seen only one specimen, has the outline of F. fonnosnm, but 

 has much closer striation, and longitudinal lines close to the median line. 



