KONGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 26. N:0 2. 185 



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

 Australian Alps! New Zealand! Houghton, Michig.! Illinois! California! Demerara! Rio Janeiro! 

 Ecuador ! 



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

 ing over to G. subclavatum var. montana by the forma Br^bissonii, and to G. Augur by smaller 

 forms of the var. Turris. 



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

 basis. L. 0,o3 to 0,05; B. 0,oo9 to 0,oi mm. Axial area narrow; central area narrow, unilateral 

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

 Syn. p. 124 PI. XXHI f. 29. G. Augur var. Gautieri V. H. Syn. p. 124 PI. XXIII f. 28. G. na- 

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



Fresh water: Belgium (V. H.), Ceyssat, Puy de Dome foss. ! Maine, Bridgetown! Waltham 

 Mass.! Mexico! Seychelles! 



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

 as a form with non-constricted valves. 



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

 to 0,025; B. 0,006 to 0,007 mm. Axial and central areas indistinct. Striae 14 in 0,oi 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 PI. Ill f 20, 21. G. crisfatumW. Sm. 

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



Fresh water: Finland! 



G. apicatum is nearly connected with G. acuminatum, f. trigonocephala, but has finer striae. 



13. G. validnm Cl. N. Sp. — V. elongated, gently biconstricted, with rostrate-apiculate 

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

 Stigma often indistinct. Striae 6 to 7 in 0,oi mm., distinctly punctate, of equal length, transverse, 

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



Fresh water: Japan, fossil in lignite (Brun Coll.)! Demerara River! 



Var. elongata. — V. very slightly biconstricted, with subcuneate apex. L. 0,i4; B. 0,oii3 

 mm. Striae 5,5 in 0,o) mm. - PL V f. 8. 



Fresh water: Demerara River! 



G. validum has the outline of G. subclavatum 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 (Aland)! New York (Niagara Falls! Genessee Falls)! Lake Pistaku 

 (Illinois)! 



G. spJicerophorum is nearly akin to G. Turris, from which it difi'ers scarcely by anything 

 but the capitate apex. 



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

 apex. Basis much narrower, obtuse. L. 0,047 to 0,05; B. 0,oii to 0,oi2 mm. Axial area narrow, 

 linear, somewhat dilated around the central nodule. Stigma distinct. Striae 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. constrictum and G. subclavatum, but differs from the 

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

 much broader ends and more distinct axial area. 



K. Vet. Akad. Handl. Band 26. N:o 2. 24 



