CHARACE^E. 331 



Carolina thirty-eight edible species of Agaricus, eleven of Boletus, nine 

 of Polyporus, seven of Hydnum, and thirteen of Clavcuria. 



(/) Polyporites Bowmani of the Carboniferous is the oldest known 

 member of this order. In the Tertiary the modern genera Lenzites, 

 Polyporus, and Hydnum are represented. 



V. CLASS CHABACE^E. 



430. In this small group of chlorophyll-bearing aquatic 

 plants the sexual organs, while still preserving essentially 

 the structure common to other Carposporeae, present con- 

 siderable modifications. The female organ consists of a 

 " central cell " or carpogonium (Fig. 227, c), which is the 

 terminal one of a row of cells (a, 

 b, c, Fig. 227). From the basal 

 cells there grow out five elongat- 

 ed cells (d, d, Fig. 227), which 

 take an upward direction and 

 surround the carpogonium ; they 

 cohere laterally, so as to form a 

 complete covering. The top of 



, . i Pig. 227,-Development of tke 



this enveloping sheath becomes carpogonium of mteUa 

 modified into a projecting crown ^^^^SS 

 of five (or by division ten) more 

 or less divergent cells (i, t, Fig. 

 227 B; and c, Fig. 228, A). 



Finally, the whole envelope be- dosed the central ceii,c; i.i,ce\\ 



J ' which form a crown upon the en- 



comes twisted, so that each en- veioping ceils. x aoo. After Sachs. 

 yeloping cell passes spirally around the carpogonium (A, 

 Fig. 228). 



431. The male organ, or antheridium, consists of a 

 globular body composed externally of eight spherically tri- 

 angular cells, called the shields, which are united by their 

 zigzag margins (a, Fig. 228, A). From the centre of each 

 shield there projects into the cavity of the antheridium a 

 cylindrical cell (manubrium), and upon each of these there 

 are borne large numbers (twenty to twenty-five) of long 

 coiled and bent many-celled filaments (b and c, Fig. 229). 

 Each filament contains from one to two hundred cells, 



