564 Transactions of the Society. 



frequently in specialized adjacent cells, which with the trichophore 

 and fcrichogyne collectively constitute, heibre fertilization the 

 procarp, and after fertilization the cystocaiy. The discovery of 

 this very remarkable and complicated reproductive apparatus is 

 due to the extensive researches of Dr. Bornet and M. Thuret,* 

 whose magnificent illustrations and lucid descriptions leave little 

 more to be expected in connection with the reproduction of the 

 Florideie. In Agardh's latest work on Algie^ Porphyra, Erythro- 

 trichia, Goniotrichum, and Bangia, genera previously classed with 

 the Floridew, are included in the TJlvacex, one leading character- 

 istic of which is the possession of true zoospores. From this it 

 appears that he does not admit Berthold's statement % that the 

 species of Porphyra possess a trichogyne and trichophore, the 

 latter eventually forming the cystocarp. 



The genus Chantransia as defined by Thuret, contained both 

 marine and fresh-water types, frequently to be met with growing 

 on other algae, under the form of minute tufts or velvety fringes, 

 and characterized mostly by the monotypic structure of the vege- 

 tative parts ; but a more extended and critical examination has 

 shown that only two of the supposed species possess antheridia, 

 trichogynes, and cystocarps ; one fresh-water, G. investiens Lenor., 

 made the type of a new genus, Balbiania, by Sirodot ; the other a 

 marine species, G corymbosa Bornet, which is therefore the only 

 true Chantransia. It has been shown by Sirodot § that many of 

 the fresh -water organisms formerly included under Chantransia, 

 are nothing more than the prothalloid stages of various species of 

 Batrachospermum, a genus of fresh-water algae belonging to the 

 Floriden?, and morphologically but little above Chantransia. 



It is interesting in connection with the development of the 

 organs of reproduction characteristic of the Floridese, to note that 

 in the genus Chantransia, where they first appear, out of numerous 

 forms which, as already explained, from an examination of the 

 vegetative parts alone, appear to be good members of the genus, 

 only two have succeeded in producing sexual organs ; the rest 

 after remaining some time as asexual forms, give origin as it were 

 to a sexual generation in Batrachospermum, whose reproductive 

 organs closely resemble those met with in Chantransia and 

 Balbiania, but in this second generation the vegetative part has 

 become rather more complex. 



A repetition of what has been described is met with in Calli- 

 thamnion, a typical Floridean genus in its most perfect develop- 



* "Recbercbes sur la jfe'eondation des Floride'es," Ann. Sci. Nat., vii. (18G7). 

 ' Notes Algologiques,' fasc. i, ii., Paris, 1876-8. 



t " Til Algernes Systematik," Lunds Arsskrift, xix. (18S2-S3) 177 pp. and 4 pis. 



X MittheiL aus der Zoolog. Station zu Neapel, iii. (1882) pp. 31)3-536, 3 pis. 



§ " Observations sur le developpemeut des algucs d'ean douce composaut le 

 genre Uatracliospcrmurn," Bull. Soc. Bot. France, xxii. (1875). 



