410 ALGiE DIATOMACEiE. [Gomphonema 



tawny, stipes subramose, frustula wedge-shaped truncate. — 

 Exilaria minutissima, Berk. Brit. Alg. p. 22. t. l.f. 1. 



Attached to sticks, stones, grass, &c, in fresh-water, Rev. M. J. Ber- 

 keley. Spring arid early Summer. — Tufts or masses several lines thick, 

 of a tawny colour ; when dry of a lively green. Mr. Berkeley thinks it 

 may be the same as the preceding, which, however, is a much smaller 

 plant, less tufted, and whitish or slightly ochraceous when dry. I have 

 therefore ventured to keep it distinct. 



3. G. minutum, Ag. (minute Gomphonema); plant forming an 

 apparently pulverulent stratum, stipes sparingly branched, the 

 frustula linear-conical globuliferous at the apex. — Ag. Conspect. 

 Crit. Diat. p. 34. 



Streams, attached to Conferv<z,&c. Appin, Capt. Car michael— Stra- 

 tum, according to Agardh, having a pulverulent appearance to the naked 

 eye, when recent ; the stipes branched or nearly simple ; the frustula 

 hyaline, with a green globule at the apex. The only specimens I have 

 seen are those in a dry state, from Captain Carmichael, and the globule is 

 not visible. It is therefore possible that I may not be correct in referring 

 it to this place. 



4. G. gemindtum, Ag. (twin Gomphonema); densely tufted 

 pale tawny, stipes elongated dichotomous, frustula somewhat 

 urn -shaped. Ag. Syst.Alg. p. 12, et Conspect. Crit. Diat. p. 35. 

 Grev. Crypt. FL t 244. 



Stones and rocks, in the beds of alpine and subalpine rivulets. Pent- 

 land hills, Mr. Amott and Dr. Greville. Not unfrequent in the High- 

 lands. Spring. — Tufts compact, distinct, half an inch to an inch or 

 more in diameter, soft and flaccid. Stipes of the same length, many 

 times dichotomous, very slender. Fruslida with a linear-cuneiform out- 

 line, tubular, at length somewhat urn-shaped, containing a green granu- 

 lar mass. 



5. G. ampulldceum, Grev. (flagon Gomphonema); densely 

 tufted, stipes elongated dichotomous, frustula in pairs but dis- 

 tinct urn-shaped rounded at the apex — Echinella ampullacea, 

 Carm. MSS. 



On rocks and stones in the river of Glenstockdale, abundant: 

 Spring and Summer. Appin, Captain Carmichael. — This species 

 seems to be indicated by Agardh, under G. gemination, in his Con- 

 spectus Criticus Diatomacearum. He there mentions an allied plant, 

 with a more rigid habit, subglobose tufts, and frustula often soli- 

 tary, urn-shaped, constricted below the apex, which is furnished with an 

 operculum : the last character I have not observed. The tufts and the 

 frustula are similar to the preceding in size; both when dry, are of a 

 greenish-gray or dirty-white colour. 



6. G. paradbxum, Ag. (doubtful Gomphonema); aggre- 

 gated yellow, stipes erect dichotomous, the frustula wedge- 

 shaped somewhat corymbose; — Ag. Syst. Alg. p. 11, et Conspect. 

 Crit. Diat. p. 34. — Echinella paradoxa, Grev. Crypt. Fl. U 25. 

 Lyngb. Hydroph. Dan. t. 70. 



Parasitic on the smaller marine Algce. Frith of Forth, Dr. Greville 

 and Mr. Amott. Appp, Captain Carmichael. Spring. — Less than a 



