168 p. T. CLEVE, SYNOPSIS OF THE NAVTCULOID DIATOMS. 



p. 68 PI. LIV f. 345. A. S. Atl. X f. 64 to 69; LXXI f. 6 to 9. V. H. Syn. p. 65 PI. Ill f. 9 

 to 11. Cymbella Encyonema Heib. Coiisp. p. 110 (1863). Encyonema maximum Wartm. Rabh. Alg. 

 Eur. N:o 1248 (1862)." 



Fresh or slightly brackish water : Sweden (Gulf of Bothnia, from Westerbotten to Roslagen ; 

 Lake Malaren)! Finland (Abo, Ladoga)! England! Belgium (V. H.), France! Switzerland (Brun), 

 Germany! Hungary (Plattensee, Grun.), Italy (St. Fiora, foss.). 



36. C. (Encyonema?) inelegans Cl. N. Sp. — V. boat-sliaped, with arcuate dorsal margin, 

 straight or slightly concave ventral margin, and broad, rounded, somewhat reflexed ends. L. 0,o.55 

 to 0,06 5; B. 0,0 2 mm. Median line parallel to the ventral margin, very excentric. Terminal 

 fissures comma-like; terminal pores near the ends. Axial area linear, rather broad. Striae on the 

 dorsal side 10 (middle) to 12 (ends) slightly radiate; striae on the ventral side 8 in 0,oi mm., 

 radiate in the middle, parallel in the ends, coarsely punctate; puncta 17 to 18 in 0,oi mm. — 

 PL V f. 1. 



Fresh water: Fall River, Oregon, foss. (Grove Coll.)! 



37. C. (Encyonema) Triangulum Ehe. (1845). — V. broad, asymmetrical, lanceolate with 

 acute ends. L. 0,04 to 0,o5; B. 0,02 mm. Median line straight, dividing the valve into a ventral 

 part half as broad as the dorsal. Terminal fissures in the ends of the valve. Axial area very 

 narrow; central area small or indistinct. Strise 9 to 11 in 0,oi mm. almost parallel or slightly 

 radiate in the ends, coarsely punctate; puncta about 10 in 0,oi mm. — Gloeonema Triangulum 

 Ehb. Abb. 1845 p. 77. M. G. XXXV A. 7 f. 10. Encyon. Triang. KtJTZ. Sp. Alg. p. 62. A. S. 

 Atl. X f. 54; LXXI f. 10. 



Fresh water: North America, New York and Pensacola (Atl.), Michigan, Dakota and Lost 

 Spring Ranch Calif.! Tasmania, Campbell Town, fossil! 



38. C. (Encyonema) turgida Greg. (1856). — V. lunate, with strongly arcuate dorsal, cen- 

 trally gibbous ventral margin, and acute ends. L. 0,05 to 0,io; B. 0,oi2 to 0,o2.s mm. Median 

 line straight, dividing the valve into a ventral part of about half the width of the dorsal. Ter- 

 minal fissures in the ends, comma-like, turned downwards. Axial area distinct, linear, scarcely 

 dilated in the middle. Striae 7 to 9 in 0,oi mm., radiate in the middle and, on the dorsal side, 

 at the ends, parallel or convergent at the ends on the ventral side, punctate; puncta 13 to 18 in 

 0,01 mm. - Greg. M. J. IV p. 5 PI. 1 f. 18. Enryon. turg. A. S. Atl. X f. 49 to 53. V. H. Syn. 

 p. 65 PI. Ill f. 12. 



Fresh water: Sweden! Finland! Movith of Jenissey! Scotland (Greg.)^ East Indies! Java! 

 Australia (Murray River)! Tasmania! New Zealand! North America (California, Mexico)! Guate- 

 mala! Ecuador! Argentina! 



This species is very variable and graduates into the following. The largest and most ty- 

 pical specimens occur in California, Mexico and Ecuador. European .specimens are smaller and 

 can only with difficulty be distinguished from the following species. 



39. C. (Encyonema) ventricosa KtJTZ. (1834). — V. lunate, with straight or centrally 

 gibbous ventral margin and subacute ends, usually turned downwards. L. 0,oi5 to 0,o36; B. 0,oo7 

 to 0,011 mm. Median line approximate to the ventral margin. Terminal nodules and fissures at 

 the ends of the valve. Axial area very narrow or indistinct. Striae 10 to 16 in 0,oi mm. slightly 

 radiate, finely punctate. Frustules enclosed in branched mucous tubes. — Frustulia ventricosa KCtz. 

 Syn. p. 11 f. 7. Uyml. ven. Bac. p. 80 PI. VI f. 16. Encyon. ventric. V. H. Syn. p. 66 PI. Ill fig. 15 

 to 17, 19. Encyon. prostratum Kt)TZ. Bac. p. 82 PI. XXV f. 7 (1844). Encyon. ccespitosum KftTZ. 

 Sp. Alg. p. 61 (1849). W. Sm. B. D. II p. 68 PI. LV f. 346. V. H. Syn. p. 65 PI. Ill f. 14; Suppl. 

 A f. 3. A. S. Atl. X f. 57, 58; LXXI f. 11, 12. Encyon. Auerswaldii Rabh. Stissw. D. p. 24 PI. VII 

 f. 2 (1853). Cymiella maculata W. Sm. B. D. I PL II f. 23. Cymb. affinis var. semicircularis 

 Lagst. Spitsb. D. p. 43 PL II f. 20. Cocconema Lunula Ehb. Am. PL I: i, f. 15 (1843). Encyon. 



