1^ 



MOSSES AND FERNS 



CHAP. 



ventral segments, and from the outer cells of the former the 

 sexual organs arise exactly as in Riccia. On the ventral sur- 

 face the characteristic scales of Riccia are absent, and are re- 

 placed by the glandular hairs found in most of the anacrogy- 

 nous Jungermanniales. 



The development of the archegonium shows one or two 

 peculiarities in which it differs from other Hepaticse. The 

 mother cell is much elongated, and the first division wall, by 



c $ 



Fig. 30. — Sphcerocarpus Californicus (?). A, Male plant, X40; ^, antheridia; B, 

 median section of a similar plant, X80; C, the apex of the same section, X240; 

 h, ventral hair. 



which the archegonium itself is separated from the stalk, is 

 some distance above the level of the adjacent cells of the 

 thallus, so that the upper cell is very much smaller than the 

 lower one. The upper cell has much denser contents than the 

 lower one, which instead of remaining undivided as in Riccia, 

 divides into two nearly equal superimposed cells, this division 



