412 ALGiE DIATOMACEiE. [Schizonema. 



Frith of Forth, growing on rocks, in small pools left by the tide, 

 Mr. Arnolt, and Dr. Greville. March. — Somewhat tufted ; the fronds 

 lax, erect, about half an inch high, olivaceous-green. Substance very 

 tenacious. 



111. Schizonema. Ag. Schizonema. 



Frustula in longitudinal series and inclosed in a simple or 

 branched, filiform, mucous or membranaceous frond. — Name; 

 °"% /< 3 W ' *° divide, and v*j,&a, a thread, or filament ; in allusion to 

 the separation of the frustules. 



1. S. quadripunctdtum, Ag. (four-dotted Schizonema) ; fila- 

 ments branched tufted, frustula oblong at first in fours, afterwards 

 scattered distinct. Ag. Syst. Alg. p. 10, et Conspect. Crit. Diat. 

 p. 21. — Bangia quadripunctata, Lyngb. Hydroph. Dan. t. 26. 

 — Monema quadripiinctatiim, Grev. Crypt. Fl. t. 286. 



On stones and rocks in the sea. Appin, Capt. Carmichnel. Frith of 

 Forth, Dr. Greville. — Tufts olivaceous-green, one to three inches in 

 length, flaccid, the filaments very slender. Frustula, or granules, at first 

 arranged in fours in a star-like manner, in a hyaline oval receptacle ; 

 they ultimately separate and assume various arrangements within the 

 tubular filaments. 



2. S. helminthosum, Chauv. ( Worm-lihe Schizonema) ; fila- 

 ments tufted irregularly branched the extremities setaceous, 

 frustula oblong elongated. Chauv. Alg. Normand. exsicc. No. 77. 

 Dub. Dot. Gall. 2. p. 985. Ag. Conspect. Crit. Diat. p. 20. 



Rocks in the sea. Frith of Forth, Dr. Greville. Summer — Tufts 

 one to three inches in length, of an opaque dull-green colour. Filaments 

 much but very irregularly branched; the branches attenuated to a 

 setaceous point. The frustula are remarkable for their length. I have 

 compared our Scottish specimens with those published by my excellent 

 friend, F'rofessor Chauvin, in his beautiful Algues de la Normandie, and 

 find them to agree in every respect. 



3. S. Dillivynii, Ag. (Dillivyris Schizonema) ; filaments 

 tufted dichotomous capillary acuminated, frustula linear-oblong 

 with a longitudinal line — Ag.Syst. Alg. p. 10, et Conspect. Crit. 

 Diat. p. 26. — Monema Dillwynii, Grev. Crypt. Fl.t.297 Con- 

 ferva foetida, Dillw. Conf. t. 104. 



On rocks, stones and Algce in the sea. Appin, Captain Carmichael. 

 Frith of Forth, Dr. Greville. — Tufts about two inches in length, of an 

 olivaceous-green colour, and often foetid odour. Filaments flaccid, 

 gradually acuminated to a sharp point. Capt. Carmichael observed them 

 to be sometimes opaque and fuscous. The plant frequently glistens with 

 a faint metallic lustre when dry. 



4. S. spadiceum, Grev. (brownish Schizonema); filaments 

 capillary tufted much branched, ramuli much divaricated. — 

 Gloionema spadiceum, Carm. MSS. 



On rocks and Algce, in the sea. Appin, Captain Carmichael. — 

 Tufts two to four inches in length, of a reddish olivaceous-green colour, 

 and often with a faint metallic lustre when dry. Filaments very slender 

 and nearly of the same thickness throughout, much branched; the 



