Callithamnion roseum is one of the longest described of the 
genus, and ought therefore, one would think, to be the best 
known. But, as with many old species, several plants which are 
now distinguished, were formerly confounded under this name, 
and thus it becomes a doubtful matter to which of the modern 
species the original synonyme vosewm attaches. ‘The species was 
first defined by Roth in his Catalecta. I have seen no specimen 
of the plant of this author, and the ¢ype which I have adopted, and 
here figure, is derived from a specimen received from Mr. Dawson 
Turner, and compared many years ago by that gentleman with 
Roth’s plant, and from another sent by Mr. Borrer, as the plant 
of English Botany. ‘These two specimens agree with each other 
and also with the specimens published by Mrs. Wyatt, in Algz 
Danmonienses. As far, therefore, as the British flora is concerned, 
our notions of Cal. roseum are tolerably definite. It would be 
very desirable were our plant compared with the herbaria of 
continental authors. 
Fig. 1. CALLITHAMNION ROSEUM :—of the natural size. 2. A pair of plumules 
and three articulations of a branch. 3. Part of a pinna, with tetraspores. 
4. A small branch, bearing a cluster of favelle. 5. Binate favelle. 6. 
Joints from the lower part of the stem :—all more or less highly magnified. 
