184 T. H. BUFFHAM ON SOME FLORIDE^. 



antheridial layer itself. It will be seen that in the latter case 

 there is an elongated gelatinous body about 20 /x high, and 7 /z 

 thick, enclosing each male cell, near the apex of which the 

 pollinoid — about 3x2 yu — is formed. (Hastings, Oct., 1893, 

 in a gathering by my wife.) 



Another alga, Gigartina mamillosa J. Ag., is almost as 

 abundant as the preceding species, but the male organs have 

 escaped my search until recently. This is the more remark- 

 able as, although tetraspores are unknown, cystocarps are 

 seldom absent from any specimen. My male example was 

 plucked from a rock by my wife. The appearance is strikingly 

 different from that of the ordinary female plant, for it is 

 thickly beset from near [the base with flattened leaf-like 

 branches arising just within the edges of the main portions of 

 the frond, and with smaller ones from the other portions of 

 the thallus. In short, the plant has some resemblance to 

 Chcetangium ornatum in G. Murray's recently published In- 

 troduction to the Study of Staivceds, Fig. 68. It is on some 

 of these leaf-like branches that the antheridia appear (Fig. 4). 

 They may sometimes be just detected by the naked eye. They 

 assume various forms : circular, dumb-bell, lobed ; and the 

 surface, with a low power, appears mottled as if made up of 

 numerous rounded groups (Fig. 5). The layer when seen at 

 the edge of the thallus projects noticeably, and portions seem 

 slightly pushed outwards (Fig. 6). There is but a thin 

 gelatinous covering, and on such a spot one may just see that 

 the structure differs from that of Chondrus, although the 

 opacity of the thallus makes it difficult. If a thin tangential 

 slice of the layer be taken the view from above is that of small 

 groups of darker bodies, about 9 /a from centre to centre (Fig. 

 7). A vertical section shows that the groups aie the pollinoids 

 in minute bunches at the extremities of articulated threads 

 arising dichotomously from the coloured cells of the thallus 

 (Fig. 8). The structure of this layer has some resemblance to 

 that of Choreocolax Polysiphonice Reinsch, figured by me (loc. 

 cit. Fig. 2), but Gigartina mamillosa is on a smaller scale, the 

 pollinoids scarcely reaching 2 /u. (Salcombe, Sept , 1895.) 

 Caution is requisite in examining this species as the antheridial 

 layer is liable to be overlaid with young Dermocarpa. This is 

 readily noticed when near the edge of a flattened branch. 



