RHODOPHYCE.E, OR FLORIDE^E 221 



viz. Gystodonium, Catenella, Euthora, and Rhodophyllis, 

 but a considerable number of exotic types, such as 

 Solieria, Rhabdonia, Eucheuma, Erythroclonium, and 

 Thysanocladia, exhibiting among them the most 

 diverse forms of thallus. In Catenella a large com- 

 pound fruit is formed by many procarpia, each with 



FIG. t>9. Catenella opuntia. a, section of fertile part of thallus showing 

 numerous trichogynes ; ft, carpogonium with trichogyne highly inaTiified 

 (After Harvey Gibson). 



its trichogyne, most of which are fertilised. The 

 gonimoblast forms chains of carpospores which 

 escape, since there is no ostiole, after rupture of the 

 cortex "already weakened by the numerous aper- 

 tures occurring in it through which the trichogynia 

 pass to the exterior," as Prof. Harvey Gibson has 

 described. 



