T. H. BUFFHAH ON REPRODUCTIVE ORGANS OF THE FLORIDE.E. 259 



clearly seen. At the base is a larger cell, and this divides radially, 

 the divisions also spreading round so that the ultimate cells form 

 the antherozoids. Fig. 3 shows this appearance under a power of 

 400. (Weymouth, Sept., 1882.) 



Almost identical in form, structure, and position are the 

 antheridia of C. tetragonum Ag., of which the preceding is held 

 by some as but a variety. It also has the male and female organs 

 intermixed, but in my specimen (Sidmouth, Aug., 1884) there 

 are many tufts with numerous antheridia alone. 



In C. Hooheri Ag. these bodies are less regularly formed, and 

 are found in groups of four or five on the upper side of adjoining 

 cells of the smaller branchlets. As they mature they coalesce and 

 form a continuous layer. (A small male plant, Weymouth, 

 Aug., 1885.) 



Dudresnaya coccinea Crouan is a very beautiful plant with any 

 power. The cystocarps are very conspicuous by their full colour 

 amongst the paler loose tufts of delicate branched filaments which 

 surround the axis. Here and there a filament on the same plant 

 divides at the summit into a loose tuft bearing the minute cells 

 which contain the antherozoids. They are similar to the antheridia 

 of Helminthora divaricata (fig. 1), but much less distinguishable. 

 (Sidmouth, Aug., 1886.) 



Glceosiphonia capillaris Carm. is another interesting plant, but 

 the branching filaments form a distinct cortex. The antheridia, 

 also on the same plants as the cystocarps, are very indistinct, 

 whitish, minute spots of small cells formed by division of the 

 cortical cells. I detected these on a specimen collected by Mr. R. 

 V. Tellam (on the Cornish Coast, July, 1887). 



In my former paper (loc. cit., p. 342) I referred to the cir- 

 cumstance that the antheridia of that ubiquitous alga Ceramium 

 rubrum Ag. had not then been found on our coasts. Not long 

 afterwards (Brighton, Sept., 1884) I took a plant of this 

 species which bore the male organs on the small lateral ramules. 

 They form a continuous layer of minute cells, but are so in- 

 conspicuous as to be unsuspected without microscopic examination. 

 They occurred on a- plant with long, very sparely-branched, fila- 

 ments. Another form of this very variable species was afterwards 

 taken. (Weymouth, Aug., 1885.) The structure and habit of 

 this are very like those of C. flabelligerum J. Ag., but it is quite 

 devoid of spines. The layer of antheridial cells is usually only on 

 one half of the filaments, but the apices of all bear them. 



