BY G. 1. PLAYFAIR. 345 



Cf. Astrid Cleve, Diat. Lule Lappmark, p. 6, T. i., f.l; P. T. 

 Cleve, Diat. Finland, p. 23. Ends conical, frustule only very 

 slightly inflated in the middle. P. T. Cleve gives stride 5 in 10/x; 

 A. Clevp, 7 in 10/x. 



P. DiVERGENS var. ELLIPTICA Grun. (PI. xlv., f.ll.) 



Long. 70, lat. 16 /x. Striae 7 in 10/x. 



Lismore(185). 



Grunow, Diat. Fr. Josefs Ld., p. 98, Pl.i., f.l9; Cleve, Syn. ii., 

 p. 79; the latter gives 75 x 15 /x, stride 8-10 in 10/x. The larger 

 sizes of F. Brehissonii type and the smaller of P. divergens var. 

 elliptica seem to be identical in appearance, cf. Lagerstedt, Diat. 

 Spetsb., PI. i., f.2a, which is accepted by Cleve as F. Brebissonii: 

 the figure gives long. 62, lat. 17 /x 



Genus N a v i c u l a Bory. 

 Navicula suBTiLissiMA Cleve. (PI. xlv., f. 12.) 



Long. 38, lat. 8, ap. 5 /x. 



Lismore(185). 



Syn., St<iuro7ieis linearis Lagerstedt, Sotv. Diat. Spetsb., 1873, 

 PI. ii,f.l3. Cf. Cleve, Diat. Finland, 1891, PL ii., f.l 5, who 

 gives 32 X 5 /x; Lagerstedt, long. 30-34, lat. 7-8 /x. A'av. linearis 

 Grun., 1860, prevents the adoption of Lagerstedt's specific name. 

 A rare diatom, known only from Lappland, Sweden, and Spitz- 

 bergen. There is a faint pseudostauros on either side of the 

 central nodule. 



DiADESMis-forms. 



N. CONFKRVACEA var. PEREGRINA (W. Sm.). 



Long. 15-20; lat. valv. 8, crass, frust. 4-8 /x. 



Lismore(178, 187, 188, 190, 192; 193, 195, 197). 



Diadesmis confervacea var. peregrina, IMol. Richm. K., PI. v., 

 f .25. The frustules are so strongly agglutinated together, that 

 the filaments always break by the valves coming apart. The 

 following species, which were also found in long ribbons, I have 

 arranged as Diadesmis: but the ribbons seem of a different 

 nature from those of jVav. confervacea, being very fragile; and, 



