INTRODUCTION TO CETPTOGAMIC BOTANY. 475 



1. Phascei, Mont. (Phascacei, Br. & Sc). 



Annual or perennial. Sporangium sessUe, or shortly pedun- 

 culate, with or without a columella, indehiscent, without any 

 trace of peristome. 



524 The numerous species belonging to this tribe, which 

 contains the simplest of all mosses, are mostly of short dura- 

 tion, and occur on newly turned up soil. The leaves are 

 rarely nerveless, and their borders composed of large cells. The 

 sporangia vary somewhat in form, and are either absolutely 

 sessile, as in Archidium (Fig. 102), or more or less shortly 

 pedunculate, and their cavity either quite free, or traversed by 

 a columella. In some of the species there are traces at first 

 of a columella, but it is soon absorbed. The spores are larger 

 than in most mosses ; in Archidium they attain such a size 



Fig. 102. Fig. 103. 



Young and old sporangium Calyptra of Voitia hyperborea, 



of Archidium, with spore from magnified, 



tlie angular side, magnified. 

 Sometimes the spores are sub- 

 globose. From Hook. Herb. 



that the cavity contains only a very few, but even these appear 

 to arise four together in the mother-cells, at least occasionally, 

 if not always. In some of the species the confervoid shoots 

 or protonema are persistent, as in P. serratum, cohcerena, &c. ; 

 in other cases they soon vanish. 



525. In P. bryoides, the peduncle is elongated beyond 

 the usual limits of the tribe, but this character is still more 

 striking in Voitia, which is, moreover, distinguished by the 

 large persistent dimidiate calyptra (Fig. 103). Species occur 

 in either hemisphere. Many European forms occur in the 



