258 T. H. BUFFHAM ON BErRODDCTIVE ORGANS OF THE FLORIDE.E. 



latter arc given in parentheses. Localities and dates are indicated 

 in the same manner. 



Porphyra-laciniata Ag. (P. linearis Grev., P. vulgaris Harv.) 

 was formerly associated with Ulva and other green plants which 

 are reproduced by zoospores, and although our knowledge of its 

 mode of reproduction is less complete than that of many others of 

 the Floridece its antheridia furnish an instructive example of the 

 simple manner in which these bodies are sometimes developed. On 

 a male plant one can observe the cells with their coloured contents 

 a short distance from the free margin of the frond. The division 

 and subdivision and gradual loss of colour can be traced until near 

 the margin there is seen a multitude of minute spherical bodies. 

 A section of the frond shows that the cells have also undergone a 

 similar subdivision in directions parallel to its surfaces, so that 

 each original cell produces 32 to 64 antherozoids. (Folkestone, 

 July, 1886.) 



In marked contrast to the foregoing is a beautiful plant, 

 Helminihora divaricata J. Ag. {Dudresnaia divaricata J. Ag.) 

 PI. XX, fig. 1, represents one of the much-branched horizontal 

 filaments which arise from the axis and form the cortex ; at the 

 apices are the antheridia, x 25. Fig. 2 shows the tips of a fragment 

 surmounted with tufts of spherical antherozoids produced by the 

 repeated division of the small cells, and somewhat spread out, 

 x 4:00. This is a very elegant and delicate object, each anthero- 

 zoid being separately seen, and but "0025 mm. in diameter. On 

 the first specimen observed (Sidmouth, Aug., 1884) the branches 

 all bore cystocarps, and the antheridia were intermixed with the 

 fruit on the principal filament. The figures however were drawn 

 from specimens taken later (Weymouth, Aug., 1885), and these 

 were entirely male plants, the whole of the frond glittering with 

 the antheridia which covered its surface. 



In Callithamnion, as in many other genera, the antheridia 

 occupy positions on the plants similar to those of the tetraspores. 

 Usually the species are dioecious, but C. brachiatum Bonnem. is 

 monoecious. The cystocarps are very conspicuous, and the 

 antheridia may very easily be overlooked. They arc found on the 

 younger filaments, and even in the same tufts touching the young 

 cystocarps. Here on an internode each antheridium is a sub- 

 globose body, the surface covered with very small colourless dots. 

 By focussing with a high power below the surface the structure is 



