KONGL. SV. VET. AKADEMIENS HANDLINGAH. HANI) 26. N:() 2. IHf) 



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

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

 Ecuador! 



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

 ing over to G. suhclavatum var. montana by the forma Brebissonii, and to G. Augur by smaller 

 forms of the var. Turris. 



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

 basis. L. 0,03 to 0,o5; B. 0,009 to 0,oi mm. Axial area narrow; central area narrow, unilateral 

 StriiB 10 in 0,oi mm. slightly radiate. — Eub. Ber. 1840 p. 211. M. G. XVII: 1, f. 35. V. H. 

 Syn. p. 124 PL XXIII f. 29. G. Augur var. Gautieri V. H. Syn. p. 124 PL XXIII f. 28. G. nu- 

 sufum Ehb. Am. p. 128. M. G. VI: 1 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. accuminafum 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 indLstinct. Strise 14 in 0,oi mm. almost 

 transverse, near the end slightly radiate, not distinctly punctate. — Ehb. Abh. 1841 p. 41(5 

 (accord, to Chase) M. G. IX: 1 f. 41? Cl. D. of Finl. p. 48 PL III f 20, 21. G. cnstatum 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, but has finer stria?. 



13. G. validum 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. Stritti 6 to 7 in (),oi mm., distinctly punctate, of equal length, transverse, 

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



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



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

 mm. Striee 5,5 in 0,o] 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 striai and broader axial area. 



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

 L. 0,03 5 to 0,04 :; B. 0,01 mm. Axial area indLstinct. Central area small, rounded. Striirie 11 in 

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



Fresh water: Finland (Aland)! New York (Niagara Falls! Glenessee Falls)! Lake Pistaku 

 (Illinois)! 



^ G. sphrBrophorum 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, with broad subtruncate and usually constricted 

 apex. Basis much narrower, obtuse. L. 0,047 to 0,05; B. O,oii to 0,012 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. Bcrggrenii resembles in outline G. constrictum and G. subclavatum, but differs from the 

 former by the median stria; 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 20. X:o 2. 24 



