to the fructification for marks of difference. Here, however, the 
characters are so broadly defined, that if we regard the fruit of 
our Seirospora as being normal, according to the view first taken 
by Mrs. Griffiths and latterly though with some hesitation and 
reluctance adopted by me, we shall be compelled to form a new 
genus for its reception. In Callithamnion the tetraspores are 
borne laterally along the ramuli; here the ramuli themselves are 
converted at maturity into strings of tetraspores; a tetraspore 
bemg formed within each of the articulations of the ramulus. 
This character is quite as strong, in a generic view, as that which 
separates any other genus of Ceramiee, and amply sufficient to 
distinguish the plant from Callithamnion. 
Additional strength has certamly been latterly given to the 
view taken by Mrs. Griffiths, by the plant having been found in 
three new and widely separated habitats, namely, in Ireland, in 
Scotland, and in Sweden. I trust, therefore, that the species is 
well established. 
The specimen here drawn is a remarkably fine one, which I 
owe to the kindness of Mrs. Wyatt who gathered it at Salcombe. 
Average specimens are not much more than half the size. 
Fig. 1. SerrospoRA GRIFFITHSIANA :—zatural size. 2, Portion of a branch. 
3. Portion of the main stem. 4. Ramulus with a cluster of tetraspores 
5. Tetraspores removed :—all highly magnified. 
