KONGL. SV. VKT. AKAOKMIENS IIANI)LIN(;AH. HANI) 26. N:() 2. 107 



Var. suhrostratd Ci,. - V. with scarcely rostrate, obtuse ends. |j. 0, la to 0,20; B. 0,045 

 mm. Strife W in (),(ii mm. coarsely punctate; puncta il to 13 in 0,01 mm. — Cymh. htteropleura 

 A. S. Atl. IX f. 3. 



Fresh water: (/anada! Danas Pond! Cherryfield ! 



Var. minor V\,. — V. with lostrate and truncate ends. L. 0,00 to 0,08; B. 0,01.1 to 0,022 

 mm. Stria' 9 in 0,oi mm., coarsely punctate; puncta 18 to 21 in 0,oi mm. — Cymh. Elirt-nh. vai". 

 Lagst. Spitsb. D. p. 42 PI. IT f. 17. Cymh. A. S. Atl. IX f. 51, 52. 



Fresh water: Spitsbergen! Beeren Eiland (Lagst.), Norway (Dovre)! Scotland (Lough Moiirnc, 

 foss.)! Jenissey! St. Flora, Italy (foss.)! 



The typical C. hcfcrojilcura is a large and cliai'acteristic boreal form. The var. minor occurs 

 at Hjerkin in Dovre and cannot be distinguislied from specimens in St. Flora deposit. The latter 

 variety diifers from C. riis^ndafa in nothing except the somewhat different shape of the ends and 

 the more coarsely punctate strife. C. anicrirana A. S. (Atl. IX f. 15, 2(^) seems to be intei-mediate 

 between C. CHSpk1at<( and (\ JietcropJenra var. minor. A similar form occurs in New Zealand at 

 Horawarra. 



32. C. oreiSfOiiica C\.. N. Sp. — V. slightly asymmetrical, lanceolate, gradually tapering 

 from the middle to the acute ends. L. 0,i ; B. 0,o2 mm. Median line almost central. Axial area 

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

 area. Stria' 17 (middle) to 20 (ends) in 0,oi mm. radiate throughout, punctate; puncta about 18 

 in 0,01 mm. forming longitudinal rows. — PI. TV f. 2."). 



Fresh water: Oregon, fossil! 



33. ('.. Molleriaiia (Irun. (1875). — V. nearly symmetrical, somewliat irregularly lanceolate, 

 obtuse. L. 0,05 to 0,06; B. 0,oi to 0,012 mm. Terminal nodules of the median line at some di- 

 stance from the ends. Axial area narrow; centi'al area large, orbicular. Stria 12 to 13 in 0,oi 

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



Fresh waterC:'): Wedel in Holstein (Atl.). 



Tt .seems doul)tful whether this form, which T know only from the figures in A. S. Atlas, 

 really be a f'ymbella. Tt has mf)re of the appearance of some form belonging to the group of 

 Nnvictila viriflula, but the stricu are I'adiate at the ends. 



34. €. (Encyonenia) lacustris Ao. (1824). — V. lanceolate, scarcely asymmetrical, with 

 obtuse or truncate ends. L. 0,o:i to 0,(m;; B. 0,oi mm. Median line nearly central; its terminal 

 nodules very distant from the ends. Axial area narrow; central area 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; lineolai about 2S in 0,oi mm. — Seldzonenia laenstre Au. 

 Syst. p. 10. A. S. Atl. LXXl f. 1 to 5. V. H. Syn. PI. XV f. 40. ColMonema suhcoherena 

 Thwaites in W. Sm. B. D. II p. 70 PI. LVT f. 353. ' Encyonnnd Ungeri Grun. in A. S. Atl. X 

 f. (33. Collcfoiinna lacusfrf V. H. Syn. p. 111. 



Fresh or slightly bracki.sh water: Hungary (Plattensee CI. M. D. N:o 108), England (W. Sm.), 

 Gulf of Bothnia! 



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

 shews that it is nearly akin to the Navicula lineolatffi. 



35. (!. (Encyonenia) prostrata Berk. (1832). — V. strongly a.symmetrical, .semielliptical, 

 with obtuse ends, frequently inclined downwards. L. 0,o4 to 0,i; B. 0,025 to 0,0.3 mm. Median 

 line straiglit; its terminal nodules considerably distant from the ends. Axial area narrow; central 

 area small, orbicular. Striae 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. PI. IV f. 3. 

 Gloeonema Leihinnii Ag. Consp. p. SI? Encyonenia jxtradoxnm Kutz. Bac. p. 82 PI. XXII f. 1 

 (1844). Encyon. prodraium Ralfs Ann. N. Hist. (I) XVI PL XVIII f. 3 (1845). W. Sm. B. D. II 



