KONGL. SV. VET. AKADEMIENS HANDIJNGAR. BAND 26. NIO 2. 167 



Var. suhrostrafa Ch. — V. with scarcely rostrate, obtnse ends. L. 0,i9 to 0, 20; B. 0, 04 5 

 min. Steiffi 9 in 0, 01 mm. coarsely punctate; puncta 9 to 13 in 0, 01 mm. — Cymb. heterophnra 

 A. S. Atl. IX f. 3. 



Fresh water: Canada! Danas Pond! Chen-yfield ! 



Var. minor Cl. — V. with rostrate and truncate ends. L. O, o c to 0,0 8; B. 0,oi5 to 0,022 

 mm. Stritt! 9 in 0, 01 mm., eoarsely punctate; puncta 18 to 21 in 0, 01 mm. — Gymh. EJirenh. var. 

 Lägst. Spitsb. D. p. 42 Pl. II f. 17. Cynih. A. S. Atl. IX f. 51, 52. 



Fresh water: Spitsbergen ! Beeren Eiland (Lägst.), Xorvvay (Dovre)! Scotland (Lougli Mourne, 

 foss.)! Jeni,ssey! St. Fiora, Italy (foss.)! 



The typical C. Jieterojilf^iira is a large and cliaraeteristie borea] form. Tlie var. minor oocurs 

 at Hjerkin in Dovre and eannot be distinguished from specimens in St. Fiora deposit. The latter 

 variety differs from C. cuf<pid(ita in nothing except the somewhat different shape of the ends and 

 the more coarsely punctate striae. C. anifricana A. S. (Atl. IX f. 15, 20) seems to be intermediate 

 between C. cuspidata and (J. heteropJeura rar. minor. A similar form occurs in Xew Zealand at 

 Horawarra. 



32. C. oregonica Cl. N. Sp. — V. slightly asymmetrical, lanceolate, gradually tapering 

 from the middle to the acute ends. L. 0,i; B. 0, 02 mm. Median line almost central. Axial area 

 narrow, .slowly dilated to the middle, where it suddenly expands to a large, subrectangular, central 

 area. Strite 17 (middle) to 20 (ends) in 0,(ii mm. radiate throughout, punctate; pimcta abont 18 

 in O, öl mm. forming longitudinal rows. — Pl. IV f. 25. 



Fresh water: Oregon, fossil! 



33. C. Mölleriaiia Grun. (1875). ~ V. nearly symmetrical, soniewliat irregularly lanceolate, 

 obtuse. L. 0,0.5 to 0,o6; B. 0,oi to 0,oi2 mm. Terminal nodnles of the median line at some di- 

 stance from the ends. Axial area narrow; central area large, orbicular. Strise 12 to 13 in 0,oi 

 mm., radiate throughout. — Grun. in A. S. Atl. IX f. 71 to 75. 



Fresh water(?): Wedel in Holstein (Atl.). 



It seems doubtful whether this form, which I know only from the figures in A. S. Atlas, 

 really be a Cymbella. It has more of the appearance of some form belonging to the groiip of 

 Navicula viridida. but the strite are radiate at the ends. 



34. C. (Eiicyoiienia) laciistris Aa. (1824). — V. lanceolate, scarcely asymmetrical, with 

 obtuse or truncate ends. L. O, os to 0,oc; B. 0,oi mm. Median line nearly central; its terminal 

 nodules very distant from the ends. Axial area narrow; central ai'ea small, irregular. Stria? 

 about 9 in 0,oi mm., divergent in the middle, convergent at the ends, in the middle alternately 

 longer and shorter, transversely lineate; lineolfe about 28 in 0,oi mm. — Schizonema lacustre Ao. 

 Syst. p. 10. A. S. Atl. LXXI f. 1 to 5. V. H. Syn. Pl. XV f. 40. Colletonema subcoherens 

 Thwaites in W. Sm. B. D. II p. 70 Pl. LVI f. 353. ^ Encyonnna Unyeri Grun. in A. S. Atl. X 

 f. 63. Colletonema lacustre V. H. Syn. p. 111. 



Fresh or slightly lirackish water: Hungary (Plattensee Cl. M. D. N:o 108), England (W. Sm.), 

 Gulf of Bothnia! 



The frustules of this species live enclosed in mucous tubes. The structure of the valve 

 shews that it is nearly akin to the Naviculse lineolatse. 



35. C. (Encyonenia) prostrata Berk. (1832). — V. strongly asymmetrical, semielliptical, 

 with obtuse ends. freqiiently inclined downwards. L. 0,04 to 0,i; B. 0,02r) to O, os mm. Median 

 line straight; its terminal nodules considerably di.stant from the ends. Axial area narrow; central 

 area small, orbicular. Strise about 7 in 0,oi mm., in the middle of inequal length, and radiate at 

 the ends convergent, transversely lineate. — Monema prostratum. Berk. Brit. Alg. Pl. IV f. 3. 

 Gloeonema Leibleinii Ag. Consp. p. 31':' Encyonema 2Mi'actoxiim KtJTZ. Bac. p. 82 Pl. XXII f. 1 

 (1844). Encyon. prostratum Ralfs Ann. X. Hist. (I) XVI Pl. XVIII f. 3 (1845). W. Sm. B. D. II 



