deseription, belong to C. pannosa, or at least to the Roundstone 
plant so named. I am indebted to my friend Mr. Thwaites, 
for suggesting that our plant (C. /amellata, MS.) might be the 
C. semiplena of Agardh, and, though I have seen no authentic 
specimen, I have little doubt that this is so. At least, the spe- 
cimen in my copy of Areschoug’s ‘ Algee Scandinavice,’ which 
is quoted by Kiitzmg under his Lezbleinia semiplena, seems 
identical with our Imish specimens here figured, but is less luxu- 
riant. ‘The species would appear to have a wide range, both in 
the warmer and colder seas of Europe. Specimens from Cher- 
bourg, communicated by J/. Lenormand, doubtfully marked 
C. pulvinata? Ag., ave very similar to those from the opposite 
shores of England. 
Fig. 1. CALOTHRIX SEMIPLENA, a mass of laminated tufts :—the natural size. 
2. Filaments from the same :—magnified. 3. Portions of filaments :—more 
highly magnified. 
