240 SEAWEEDS 
sation is the same in this genus as in Dudresnaya 
(Fig. 81). The carpogonial branches and the cor- 
responding but more numerous branches that bear 
the auxiliary cells, are found together in special 
fertile portions of the cortex of the thallus. After 
fertilisation, this cortical tissue, having undergone 
Fic. 82.—Polyides rotundus. a, procarp with trichogyne and ooblastema ; 
b, ooblastema filament fertilising auxiliary cell highly magnified. (After 
Thuret and Bornet.) 
considerable development, contains close together 
numerous gonimoblasts, nearly all the cells of which 
eventually give rise to carpospores. 
Squamarice. 
The thallus of the Sguamarice: is commonly minute 
and encrusting or consists of flat foliar expansions of 
tissue, in most cases encrusted with carbonate of lime. 
In this case, as in Polyides, the carpogonial branches 
