220 BRITISH SEA-WEEDS. 



lace-like strings, at the tips of the branches. — Seibospoea, 

 from the Greek seira, a chain, and sporos, a seed. 



This genus was founded by Dr. Harvey, for the re- 

 ception of a new British species, discovered by Mrs. 

 Griffiths in 1838. He thus alludes to it in the ' Phy- 

 cologia Britannica' : — " I was not so confident of its 

 claims to this distinction [that of being a new species], 

 and first described it as a variety of Callithamnion versi- 

 color, chiefly remarkable for a curious modification of 

 fruit. There is, indeed, a close resemblance to strong- 

 growing plants of C. versicolor, so close that we are 

 driven to look to the fructification for marks of dififer- 

 ence. 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, — atetraspore being 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 Ceramiacea, and 

 amply sufficient to distinguish the plant from Calli- 

 thamnion." Professor Agardh, on the other hand, 

 maintains that the plant is a true Callithamnion, and 

 describes it as C. seirospermum. 



Seirospora Griffithsiana. Mrs. Griffiths's Seiro- 

 spora. 



Trends growing singly or in tufts, from one to three inches 



