Fragilaria.] ALGtf: DIAT0MACE7K. 403 



fragile filaments, separating at the striae (not cohering at their 

 angles). — Named from their fragile character. 



1. F. pectinate, Lyngb. (pectinated Fragilaria); filaments 

 rigid attenuated densely striated, the joints 3 — 4 times broader 

 than they are long. Lyngb. Hydroph. Dan. p. 184. t. 63. Ag. 

 Syst. Alg.p. 7 — Conferva pectinate, Dillw. Conf. t. 24. E. Bot. 

 t 1611. 



Rivers and stagnant waters. Near London, Mr. Dillwyn. Hurst- 

 Pierpoint, Sussex, Mr. Borrer. Appin, Capt. Carmichael. Near Edin- 

 burgh, Dr. Greville. Spring. — Exceedingly fragile. The fi laments are of 

 a very pale grayish-green hue, often quite pellucid, and, when dry, be- 

 coming pulverulent and somewhat glistening, scarcely adhering at all to 

 paper. 



2. F. durea, Carm. (golden Fragilaria); mucose, filaments very 

 fine gradually attenuated, the joints 2 — 3 times broader than they 

 are long often punctated in the centre. — Carm. MSS. 



Parasitic on Algcc, in the sea. Appin, Capt, Carmichael. — Filaments 

 half an incti or more in length, not fragile, of a golden or bright 

 olivaceous-yellow colour, apparently of a mucous substance, adher- 

 ing very closely to paper. The joints have sometimes the appear- 

 ance of being traversed by a very fine transverse line, and in a drawing 

 by Captain Carmichael, are represented as either marked with two 

 minute globules, or with a single pellucid white oval spot. 



3. F. diatomoides, Grew (Diatoma-lihe Fragilaria); filaments 

 very pale yellow pellucid densely striated somewhat flaccid, 

 the striae about five times broader than they are long. 



Parasitic on Algce, in the sea. — The filaments are very minute, with 

 somewhat of the habit of Diatoma striululum. They are not fragile, 

 but, on the contrary, are sometimes seen folded ami doubled with- 

 out fracture. I have not been able to ascertain the exact form of the 

 joints; whether each of the stria; is of itself a joint, or whether the joints 

 themselves (which is more probable) are striated. 



4. F. striufida, Ag. (banded Fniti'ilnria); filaments brownish- 

 green elongated gradually attenuated, the joints nearly equal in 

 length and breadth transversely striated. — Ag. Syst. Alg. />. 7. 

 (not of I.i/nqh.) — Conferva striatals, .////y. /)<<<id. 1). So. 7. 

 (not of F. Bot.) 



Parasitic on the smaller filiform marine Alg<B. Appin, Captain Car- 

 nnchaeL — This plant seems to be intermediate between Diatom* and 

 Fragilaria ; the densely striated joints bearing some resemblance to UlOM 

 Of 1>. striatiitiou. 'I he Jilumtnts, however, are mm b finer, dUtinetly 

 attenuated, and I ba\e not been able to detect any coin reiuv at the 



angles of the articulation. I have followed Agardh in adopting tne 

 name from the Decadet of Alga, published b\ Jurgens; the specfea fig- 

 ured b\ Lyngbye under the same appellation being evidently something 

 else 



.'). I . ■ *»///, rtoul, v. Grey, (i '<>//(', rru-liJ,; /'nigdn/,i); filaments 

 elongated attenuated eonipie--ed exeessi vel v fragile, the joints 

 about half ai long M thev are broad. 



