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distinct from them all, yet there are so many intermediate forms, and 

 these species verge into each other so frequently, that we should not 

 wonder if the present should ultimately lose its rank as a species, and 

 be glad to put up with that of a variety. 



We have not seen any well authenticated specimens, and none in fruit, 

 and prefer giving the characters of the species as given in Phycologia 

 Britannica to any we could form from doubtful specimens. 



From C roseum it seems to differ in its short, erect pinnules, increas- 

 ing in length upwards, and the same characters, together with the 

 solitary tetraspores, separate it from C. iwlyspermum. 



We are not aware that any really well authenticated specimens of 

 G. affine have been met with since its discovery on the shores of Bute by 

 Dr. Greville. 



CALLITHAMNION AFFINE. 



EXPLANATION OF DISSECTIONS. 



Fig. 1. — Branchlet with tetraspores. 

 2. — Tetraspore from same. 

 3. — Branchlet with favellte. 



4.— Portion of stem. 



All magnifiecl. 



