five times longer than broad, with a wide limbus, and narrow bag of endo- 
chrome, destitute of veins: articulations of the lesser branches and ramuli 
about twice as long as broad. Tetraspores roundish, sessile on the inner 
face of the pinnz, one or several on each pinna; sometimes containing 
eight grams, each of which at maturity separates into four pieces (and 
becomes a tetraspore! [fig. 4] ). On some individuals the place of tetra- 
spores is supplied by clusters of hyaline cells, collected in dichotomous 
threads, which are supposed to be antheridia (fig. 7,8). Favelle (fig. 5) 
two-lobed, containing many large grains. Colour, a fine deep lake, or rosy- 
red, brownish toward the base: staining fresh water carmine. Substance 
rather rigid when fresh, soon becoming flaccid, and closely adhering to paper. 
ee 
This very handsome species, whose essential character consists 
in having the lower half of its plumules bare of ramuli, while the 
upper is pinnated, the pinne spreading hike the rays of a fan, 
was first discovered, about forty years ago, by Mr. Borrer of 
Henfield, who has added so much to our knowledge of British 
Botany, and whose zeal in the pursuit of his favourite science is 
still as ardent as ever. ‘This, one of his early discoveries in a 
tribe of plants which he very successfully studied, has been 
consecrated to his honour by Sir James E. Smith. 
It is nearly related to several other species, especially to C. 
roseum, C. polyspermum, and C. tripinnatum; from the two 
former of which it is known by the shape of its plumules, from 
the latter, chiefly by the absence of the axillary ramulus. 
Unlike as, at first sight, this plant may appear to C. gracillimum, 
very luxuriant specimens closely resemble that species in habit, 
and exhibit a nearer approach m microscopic character than 
could be supposed. I unhesitatingly refer Agardh’s C. seminu- 
dum, which I have received from that author himself, as well as 
from several other continental friends, to our Borreri: they are 
undistinguishable. The noblest specimens of this species which 
I have seen, are those sent to me by my kind friends at Plymouth, to 
whose liberality I ain indebted for a bounteous supply. On some 
of these I have observed, (and Mrs. Griffiths has, independently, 
made the same observation,) that the ¢e¢raspores, so called, contain 
eight sporules, and that each of these at maturity becomes a 
tetrasporule! On other individuals from the same locality we 
find the place of tetraspores supplied by those little tufts of 
glassy cells which, in this genus, obtam the name of autheridia. 
Fie. 1. CaLiirHaMNion Borreri :—of the natural size. 2. Part of a branch 
~ with plumules. 3. A pinna with tetraspores. 4. Compound tetraspores. 
5. A ramulus with favella. 6. Spores from the same. 7. A plumule with 
antheridia. 8. Pinna.of the same. 9. Joints of a main branch, with 
radicular process :—aWl more or less magnified. 
