83 SPH^ROCOCCOIDE^. v. 



twenty fathom water. Authors enumerate many forms which are pi-obably but 

 variable shapes assumed by the same species at diflferent times. Thus M. membran- 

 acea^farinosa^verrucata and pustulosa of Lamouroux, appear scarcely to diflFer from 

 each other except in age and luxuriance. By Dr. Johnston the whole are regarded 

 as abnormal states of Corallina officinalis. 



Order IV. SPH^ROCOCCOIDE^. 



J. Ag. Sp. Gen. and Ord. Floridearum, p. ix. Part of Delesseriece and Sphcerococ- 

 coidew, J. Ag. Alg. Medit. p. 116 and 148. and of Endl. ^d. Suppl. Harv. Man. Ed. 

 2, 4-c. 



Diagnosis. Rosy, purplish, or blood red sea-weeds, with an inarticulate, cartila- 

 ginous or membranaceous, leaf -like or filiform frond, composed either of polygonal 

 or of cylindrical cells. Conceptacles with or without a terminal pore. Spores 

 roundish or elliptical, formed in moniliform filaments rising from the basal pla- 

 centa, all the cells of the spore-threads gradually changing into spores. Tetraspores 

 variously disposed. 



Natural Character. Root almost always discoid, rarely branching. Frond 

 much diversified in habit, structure, and colour. Most of the North American 

 genera are more or less perfectly leaf-like ; the leaf, in the least organised, being an 

 expansion of irregular form, cleft either vertically or laterally, without symmetry, 

 and destitute of central rib or of veins. In others the lower part of the frond is 

 thickened in the centre into a broad, sub-defined midrib, which becomes less 

 evident toward the upper portion of the membrane, and gradually disappears 

 where the lacinioB become expanded. In others numerous irregular veins, which 

 are confluent toward the base of the frond, spread out one from another like the 

 rays of a fan and traverse a greater or less portion of the membrane, generally 

 becoming obsolete in its upjjer divisions ; sometimes standing apart and sometimes 

 anastomozing. In others — and these are the most completely organized — the leaf- 

 like body is symmetrical, furnished with a percurrent, filiform midrib, which is a 

 continuation of the stipes or root-stem, and which becomes stem as it is gradually 

 divested of the membraneous border. This takes place with age, and thus old 

 fronds of the same species have often a much branched stem bearing numerous 

 leaves ; all which fronds originated in a single leaf whose stripped midrib was 

 converted into stem, and then put forth new frondlets, to undergo a similar 

 metamorphosis. The only North American genus with filiform fronds is Graci- 



