90 



MOSSES AND FERNS 



CHAP. 



In the ordinary form four sets of segments are cut off, dorsal 

 and ventral, as in Riccia or Sphcerocarpus, and two sets of 

 lateral ones. In Pcllia calycina the apical cell shows a similar 

 form, but in P. epiphylla (Fig. 42, D, E), another type is 

 seen. Here, while the surface view is the same as in P. caly- 



per. 



A. 



FIG. 41. A, Pallavicinia cylindrica, X4; per, the elongated perianth; B, Ancura pin- 

 natifida, X6; ^, archegonial branches; C-E, Fossombronia longiseta, X4; F, Blasia 

 pusilla, X4> 



cina, in vertical section the cell is nearly semicircular, i. e., here 

 there are but three sets of segments, two lateral ones and a 

 basal one, extending the whole depth of the thallus, and only 



