KONGL. SV. VET. AKADEMIENS HANDLTNGAR. BAND 26. N:0 2. 119 



Var. similis Grun. (1880). — V. linear, with obtuse ends. L. 0,io to 0,2; B. 0,02 to 0,o24 

 mm. Median line central, slightly sigmoid, ending below the apices of the valve. Central area 

 small. StriEB equidistant, 16 to 17 in 0,02 mm. — Pleur. simile Grun. A. D. p. 56. Per. VII f. 27. 



Fresh or brackish water: Lagos (Grun.), Java! Samoa (Grun.), Tasmania! China! Barbados! 



Var. sinensis Ehb. (1847). — V. gibbous in the middle and with incrassate ends. L. 0,i to 

 0,2; B. 0,013 to 0,022 mm. Median line strongly flexuose. T.S. : L.S. 'Vi? in 0,oi mm. — Nav. 

 sin. Ehb. Ber. 1847 p. 485 (accord, to Chase). M. G. XXXIV, 7. f. 11. Per. VII f. 11. PI sin. 

 var. ealcuttensis Grun. A. D. p. 57. Per. VII f. 12. 



Var. calif ornica Grun. (1879). — V. linear, slightly sigmoid, with gradually attenuated ends. 

 L. 0,25 to 0,28; B. 0,028 mm. Transv. and longit. strise equidistant, 14 to 15 in 0,oi mm. — 

 Pleur. bait. var. calif. Grun. in CI. M. D. N:o 246. Per. VII f. 22. 



Brackish water: California! 



23. G. diminutnm Grun. (1880). — V. linear, with obliquely truncate and rounded ends. 

 L. 0,1 to 0,11; B. 0,016 mm. Median line strongly flexuose, excentric towards the ends. T.S. : L.S. 

 'V22- '®/24. ^^26 in 0,01 mm. — Pleur. (bait, var.?) dim. Grun. A. D. p. 56. Per. VII f. 31, 32. 



Marine: Balearic Islands! Adriatic (Grun.)! 



Var. constricta Grun. (1880). — V. gibbous in the middle and at the ends. L. 0,i; B. 0,oi3 

 mm. T.S. : L.S. ''V23 in 0,oi mm. — Pleur. (bait, var.?) constr. Grun. A. D. p. 57. Per. VII 

 f. 13. Pleur. reversum Greg. D. of Clyde p. 530 PI. XIV f. 105. Per. VII f. 10? 



Marine: Adriatic (Grun.). 



PI. biharense Pant. Ill PI. XLII f. 581 seems to be an akin form. 



24. G. Waiisbecliii Donk. (1858). — V. linear, tapering towards the slightly curved and 

 obliquely rounded ends. L. 0,ii to 0,i7; B. 0,oi5 mm. Median line excentric, sigmoid. T.S. : L.S. 

 "Au. -"As in 0,01 mm. — Pleur. bait. ^ W. Sm. B. D. PL XXII f. 207 /?. PI. Wansb. Donk. 

 T. M. S. VI p. 24 PL III f. 7. Per. VII f. 23. 24. 



Brackish and marine: Sea of Kara! North Sea! 



Var. Peisonis Grun. (1860). — L. 0,09; B. 0,oi mm. T.S. : L.S. ^y^., ai-s/^g in 0,oi mm. — 

 Pleur. Peis. Grun. Verb. 1860 p. 562 PL VI f. 8. P. Spencerii var. Peis. Grun. A. D. p. 60. 

 Per. VIII f. 27. 



Brackish water: Sonderburg (Grun.), Neusiedler See, Hungary (Grun.)! 



Var. subsalina Per. (1891). — L. 0,12 to 0,17; B. 0,012 mm. T.S. : L.S. 'Vas- — Pleur. 

 Spencerii var. subs. Per. p. 24 PL VIIL f. 16, 17. 



Brackish water: Medoc, France (Per.). 



25. G. (Khoicosigma) aixticum Cl. (1873). — V. slightly sigmoid, tapering from the middle 

 to the subacute or obliquely rounded ends. L. O.07 to 0,2; B. 0,oi4 to 0,02 mm. Median line more 

 sigmoid than the valve, sometimes slightly sinuose. T.S. : L.S. ^Vas' ^Vsoi "'/so in 0,oi mm. 

 Frustule more or less arcuate to almost straight. — Ehoicosigma arcticum Cl. D. Arc. Sea p. 18 

 PL III f. 16. Per. X f. 16, 17. 



Marine: Greenland! Spitsbergen! Sea of Kara! Finmark! Grip in Norway! Firth of Tay! 

 Barbados! Kerguelens Land! 



This species varies in amount of flexure. Specimens from Kerguelens Land, named by 

 Grunow Donhinia subflexuosa (Icon. n. PL VI (Part II PL I) f. 3, 4), are straight, so also are speci- 

 mens from Barbados, but othelwisei they differ in nothing of importance. The ends are subacute 

 or obliquely rounded according to the position of the valve. 



As a Var. irregularis Pbraaallo has (p. 33 PL X f. 18) figured an asymmetrical form from 

 the North Sea, which requires a more accurate study. 



26. (Donkinia) rectum Donk. (1858). — V. convex, linear, straight, with obliquely rounded 

 ends. L. 0,ii to 0,23; B. 0,oi3 to 0,02 mm. Median line strongly excentric and sigmoid. Transverse 



