30 ASTRID CLEVE, ON RECENT FRESHWATER DIATOMS. 



E. triodon Ehb. — V. H. XXXIIl, 9. 



Striae 17 in 0,oi mm., eqnidistant, and reaching both 

 margins. 



Kv. 2S, Nu. 3, 5, 11, 17, 18, 19, 37, 39, 41, Ks. 20, Jm. (3, 

 31, Ö.-K. 7, 33, Na. 35, Tj. 42, Gl. 43, Gl. D. 44. — Freqnent. 



E. polyglyphis Grun. — V. H. XXXIV, 33. f. 5-, 6- and T-gly- 



phis Ehb. 



Striae 14 to 15 in O, o i mm. End-nodules near the ventral 

 margin at some distance from the ends of the valve. 



Kv. 28, Nu. 5, 18, 19, 37, 41, Jm. 6, 31, Ks. 15, 20, V. 12, 

 S.-K. 22, 33, Na. 35, Tj. 42, Gl. D. 47. — Freqnent. 



Is perhaps but a variety of the following species, from 

 which it differs only by the elevations on the dorsal side. 



E. incisa GréG. — V. H. XXXIV, 35 a. 



Striae and end-nodnles as in E. polygiyphis. Ends acnte. 



Kv. 1, 9, K), 2i], 32, Jm. G, Ks. 15, 20, Km. 10, Ll. 21, 

 Na. 35, Tr. 38, Tj. 42. — Freqnent. 



Var. obtiisiuscula Grun. — V. H. XXXIV, 35 b. 



Valve tapering towards the obtuse ends. 



Jm. (i. — Rare. 



Var. obtusa Grun. — V. H. XXXIV, List of eontents. 



Ends rounded-obtnse, as broad as the middle of the valve 

 or almost so. Striae 10 to 17 in 0,oi mm. 



Nu. 5, 17, 18, 19, 37, Ks. 15, 20, Jm. (>, 31, S.-K. 22, 

 Tr. 38, Tj. 42, Gl. 43. — Freqnent. 



E. faba Grun. in V. H. XXXIV, 34 has the same ontline 

 as this variety, but has more distant striae. 



The size of E. incisa var. obtusa is very variable, from 

 0,017 to 0,0 6 5 mm. in length. The larger forms sometimes 

 graduate to E. parallela Ehb. 



E. lunaris (Ehb.) Grun. — V. H. XXXV, 3, 4, 0. 



Valve arcuate, narrow linear, with obtuse to subacate 

 ends, 0,05 to 0, 09 mm. in length, 0,oo5 mm. in breadth. Striae 

 eqnidistant, 14 to 16 in 0,oi mm. 



Kv. 26, Km. 30, S.-K. 33, Gl. 43, Gl. D. 44, Ke. 49. — 

 Not rare. 



Var. subarcuata Grun. — V. H. XXXV, 2. 



Smaller, with closer striae. Valve 0,oi6 to 0,04 mm. in 

 length, 0,002 to 0,004 mm. in breadth. Striae 19 to 20 in O, o 1 mm. 



