KONGL. SV. VET. AIvAl>EMIENS HANDLINGAR. BAND 26. N:0 2. 185 



Fresli water: Finland (Padasjoki)! Bengal! Australia, North Anstralia! Murray River! 

 Australian Alps! New Zealand! Hoiighton, Micliig. ! Illinois! California! Demerara! Rio Janeiro! 

 Ecuador! 



G. acuminatum comprises a number of forms, exceedingly variable in size and outline, pass- 

 ing över to G. suhclavatum var. monfana by the forma Bi'ébissonii, and to G. Augur by smaller 

 forms of the var. Turris. 



12. tr. Augur Ehb. (1840). — V. clavate, with broad, truncate-apiculate apex and narrow 

 basis. L. O, os to O, os; B. 0,oo9 to 0,oi mm. Axial area narrow; central area narrow, unilateral 

 Striai 10 in 0,oi mm. slightly radiate. — Ehb. Ber. 1840 p. 211. M. Gr. XVII: i, f. 35. V. H. 

 Syn. p. 124 Pl. XXIII f. 29. G. Angur rar. Gautieri V. H. Syn. p. 124 Pl. XXIII f. 28. G. na- 

 sufum Ehb. Am. p. 128. M. G. VI: i f. 37? 



Fresh water: Belginm (V. H.), Cey.ssat, Pny de Dome foss.! Maine, Bridgetown! Waltham 

 Mass.! Mexico! Seychelles! 



G. Augur is closely connected with G. accuminatum var. Turris, of which it may be regarded 

 as a form with non-constricted valves. 



G. apicatum Ehb. (1841). — V. clavate, not biconstricted, Avith acnminate apex. L. 0,022 

 to 0,025; B. 0,006 to 0,007 mm. Axial and central areas indistinct. Striaj 14 in 0, 01 mm. almost 

 transverse, near the end slightly radiate, not distinctly punctate. — Ehb. Abh. 1841 p. 416 

 (accord. to Chase) M. G. IX: 1 f 41? Cl. D. of Finl. p. 48 Pl. III f. 20, 21. G. crisfatum W. Sm. 

 B. D I Pl. XXVIII f. 239? Heib. Consp. D. D. V f. 17? 



Fresh water: Finland! 



G. apicatum is nearly connected with G. acuminatum f. trigonocephala, bnt has finer strise. 



13. €r. validum Cl. N. Sp. — V. elongated, gently biconstricted, with rostrate-apicnlate 

 apex. L. 0,06 5; B. 0, 01 mm. Axial area linear, moderately broad, not dilated in the middle. 

 Stigma often indistinct. Sti'iai 6 to 7 in 0, 01 mm., distinctly punctate, of equal length, transverse, 

 but radiate at the apex. — Pl. V f. 9. 



Fresh water: Japan, fossil in liguite (Brun CoU.)! Demerara River! 



Var. elongata. — V. very slightly bicon.stricted, with .subcuneate apex. L. 0,14; B. 0,oii3 

 mm. Strise 5,5 in 0,oi mm. Pl. V f. 8. 



Fresh water: Demerara River! 



G. validum has the outline of G. suhclavatum var. montana, from which it differs by its 

 coarser striae and broader axial area. 



14. G. sphaerophorum Ehb. (1845). — V. clavate, with capitate apex and narrow basis. 

 L. 0,035 to 0,047; B. 0,01 mm. Axial area indistinct. Central area small, rounded. Striae 11 in 

 0,01 mm., nearly transverse, punctate. — Ehb. Ber. 1845 p. 78 (fide Chase), V. H. Syn. Pl. XXIII f. 30. 



Fresh water: Finland (Åland)! New York (Niagara Falls! Genes.see Falls)! Lake Pistaku 

 (Illinois)! 



G. sphferophorum is nearly akin to G. Turris, from which it differs scarcely by anything 

 but the capitate apex. 



15. G. Berggrenii Cl. N. Sp. — V, clavate, witli broad subtruncate and usually constricted 

 apex. Basis miich narrower, obtuse. L. 0, 04 7 to 0,05; B. 0,oii to 0,012 mm. Axial area narrow, 

 linear, somewhat dilated around the central nodule. Stigma distinct. Striaj coarse, 10 to 11 in 

 0,01 mm. distinctly punctate, slightly radiate. — Pl. V f. 6, 7. 



Fresh water: New Zealand (Waitangi! Lake Rotorua! etc). 



G. Berggrenii resembles in outline G. constrictiini and G. suhclavatum, but differs from the 

 former by the median strise not being alternately longer and shorter, and from the latter by its 

 rauch broader euds and more distinct axial area. 



K. Vet. Akad. Haudl. Band 36. Nio S. 24 



