147 



257. tetrag^onum [The four-angled Callithammon)) outline of the 

 frond ovate; stem cartilaginous, rub-simple, setaceous, some- 

 what opaque, vein ^ , sel w ith Bubquadri&rious lateral bran 

 furnished sometimes w ith a seo< nd or third series; penulti- 

 mate branches pellucidlj jointed, sleti with 

 Bhort, alternate, patent, Level-topped plumules, the Ion 

 which arc simply pinnate, the Bub-bipinnate ; ramuli in- 

 curved, narrowed at the base, sudden!) acuminate, their ar- 

 ticulations once and a half as Long as broad, constricted at the 

 joints; tetraspores ?ery minute, oval, near the tips of ( 

 nmli, An. Sp. r. 2. p. 176. (Atlas, PL LVll. Fig. 264.) 



Ceramium tetragonum, An. Conferva tetragona, With. 

 Hah. Parasitical on the Larger Alga?; commonly on the fronds of 

 Laminaria digltata. Annual. Summer. 

 CaUithamnion tetragonum, when fully grown, is one of 

 the large8l and most robust and shrubby of the 1 >ri t isli 

 species of this charming genus, and. seen under water, is 

 an object of much beauty. In drying, though it suffi- 

 ciently retains its form, it Loses considerably in elegance, 

 from the pressing together of the delicate quadrifarious 

 ramuli, which in a state of nature stand out from the 

 branehlets, giving to the different parts of the frond a 

 roundness, without confusion or matting together of t lie 

 minutest part. These, in dried specimens, become 

 founded together. Jt rapidly changes colour in fresh 

 water, assuming a brilliant orange-tint, and giving out a 

 coloured powder. Though a species of large Bize, its 

 tetraspores are exceedingly small, much smaller in propor- 

 tion than those of most other species, and, being borne 

 near the tips of the smaller and more crowded ramuli, may 

 easily escape detection. The favella, on tin 4 contrary, 

 are of large size, and easily Been. 



258. brachiattim {The armed CaUithamnion) ; outline of the 

 frond lanceolate; stem cartilaginous? subsimple, setaceous, 



somewhat opaque, veiny, set with BUbquadrifarioUB, lateral 



branches, often tarnished with a second Beriee ; penultimate 

 branches peilucidly jointed, slender, elongate, Bet with Bhort, 

 alternate, very erect, level-topped plumules, the Lowermost 

 of which are mosl Bimple; ramuli erect, subulate, not nar- 

 rowed at base, gradually tapering to a line point, their ar- 

 ticulations twice as long a- broad, cylindrical ; tetraspores 

 minute, oval, near the tips of the ramuli, Bo \ 



PL L\ 1. Pig. 2 

 Callithaiiniioii Harveyanum, J. An. ('. granulatum, 11 



