KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 27. N:() 3. 175 



line, reaching to the margin, no areas and fine strise, radiate throughout, about 25 in 0,oi mm. 

 Diat. of Finland p. 51 PL III f. 8 (9?) 



Fresh water: Sweden (liyssby in Calmar Lan, baltic freshwater deposit from the Ancylus- 

 epoch), Abo, Finland! 



5. C. dirupta Greg. (1857). — Broadly elliptical to almost orbicular. Upper V. with 

 linear, usually sigmoid, axial area. Lower 'V. with more or less distinctly sigmoid median line 

 and the terminal fissures in contrary directions. Central nodule transversely dilated to an out- 

 wardly narrowing fascia. 



Var. typica Cl. — L. 0,026 to 0,o6i; B. 0,oi8 to 0,o5 mm. Upper V. with linear not sig- 

 moid axial area. Striae about 17 in 0,oi mm. punctate; puncta forming undulate longitudinal 

 rows. Lower V. with very slightly sigmoid median line. Central area transversely dilated to a 

 fascia not reaching to the margin. Striae 20 in 0,oi mm. — C. dirupta Greg. D. of Clyde p. 491 

 PL IX f. 25. A. S. N. S. D. PL III f. 21. V. H. Syn. p. 13.3 PL XXIX f. 13 to 15. C. diaphana 

 W. Sm. B. D. p. 22 PL XXX f. 254 partim (1853)? C. delicata A. S. Atl. CXCVl, 24? Probably 

 also C. oceanica, C. limhata and C. fasciata Ehb. 



Marine: Greenland! North Sea! Mediterranean Sea! China! Behring's Island! Tahiti (Grun.), 

 Cape of Good Hope (Grun.), California! Galapagos Islands! Colon! 



Var. dubia Grun. (1867). — Smaller. Striae 22 0,oi mm. Central nodule rarely, terminal 

 nodules never, transversely dilated. — Novara p. 14. 



Marine: S:t Paul (Grun.). 



Var.? Beltmeyeri Jan. (1894). — L. 0,0*; B. 0,027 mm. Upper V. with lanceolate, not .sig- 

 moid area. Striae 12 in 0,oi mm. crossed by 4 to 8 blank bands. — A. S. Atl. CXCVI, 22, 23. 



Marine: Leton Bank (Atl.), Pensacola (Atl.)? 



Var. flexella Jan. Rab. (1862). — L. 0,02 to 0,03; B. 0,02 to 0,o3 mm. Upper V. with 

 narrow, lanceolate axial area. Striae 20 in 0,oi mm. crossed on each side of the area by about 4 

 linear, curved blank bands. Lower V. with sigmoid median line, reaching to the ends, and trans- 

 verse central area. Striae about 19 in 0,oi mm. — C. flexella Jan. Rab. D. Honduras p. 7 PL I 

 f. 11. G. dir. var. flex. V. H. Syn. PL XXIX f. 16, 17. 



Marine: Mediterranean Sea! Adriatic! Honduras (Jan. Rab.). 



Var. antarctica Grdn. (1881). — L. 0,042; B. 0,035 mm. Upper V. with narrow, linear axial 

 area. Striae about 15 in 0,oi mm., punctate; puncta forming longitudinal rows, about 13 in 0,oi 

 mm. Lower V. with nearly straight median line, ending at some distance from the margin in trans- 

 verse terminal areas, turned in contrary directions. Striae 11 in 0,oi mm. distinctly punctate; 

 puncta forming irregularly undulating longitudinal rows, about 11 in 0,oi mm. — V. H. Syn. 

 PL XXIX f. 18, 19. C. dir. var. major Grcn. Novara p. 14? 



Marine: New Zealand (Grun.), China! 



Var. californica Cl. — L. 0,045 to 0,07; B. 0,o3 to 0,o6 mm. Upper V. with slightly sig- 

 moid, lanceolate axial area not dilated in the middle. Stria? 11 to 16 inO,oi mm. of large, distant 

 puncta, forming undulating, longitudinal rows, about 9 in 0,oi mm. — A. S. Atl. CXCVI, 17, 18(?) 



Marine: California fossil at S:ta Martha and S:ta Monica (Deby Coll.)! Moron, Spain, fossil 

 (Grove Coll.)! 



Var. deeipiens Cl. (1873). — L. 0,025 to 0,06; B. 0,o34 to 0,04 mm. Upper valve with sig- 

 moid axial area in the middle dilated to an orbicular space. Striae 16 to 20 in 0,oi mm. punctate; 

 puncta (10 in 0,oi mm.) forming irregularly decussating rows (14 in 0,oi mm.). Lower V. with 

 sigmoid median line reaching nearly to the ends. Striae 11 to 12 in 0,oi mm. punctate; puncta, 

 about 14 in 0,oi mm., becoming larger outwards. — G. decip. Cl. D. Arct. Sea p. 14 PL I f . 6 

 (Lower V.). G. arcticum Cl. 1. c. PL II f. 11 a (Upper V.). 



Marine: Arctic America! Greenland! Finmark! Behring's Island! 



