INTRODUCTION TO CRYPTOGAMIC BOTANY. 



435 



G. Marchantioides occurs also at Buenos Ayres and the Swan 

 River. Sphcerocarpus (Fig. 90, a, b, c) has superficial fruit with 

 a sessile or pedicellate proper involucre. The species occur 

 in temperate parts of either hemisphere. The most curious 

 genus of all is Riella (Fig. 90, d to g, formerly Durima* 



Fig. 90. 



a. SphcBTOcarpus ierrestris, slightly magnified. From a Lyons specimen 

 given me by Dr. Montagne. 



b. A young mother-spore before division, together with an old triple 

 spore, with its areolate verrucoae surface. From Moug. and Nest., 

 No. 1045. 



c. One of the cells of the wall of the sporangium filled with starch 

 grains. 



d. Ridla helicophylla, male and female, nat. size From specimens 

 given me by Durieu de Maisonneuve. 



e. Perianth and inclosed sporangium. 

 /. Sporangium. 



g. Orifice of sporangium. 



which differs from the rest in its erect habit. The stems are 

 branchless and have a distinct wing or leaflet, forming a con- 

 tinuous spiral round the stem, much after the fashion of the 

 stomach of a shark. In the male plant the edge of the frond 

 bears the antheridia ; in the female the fruit springs from the 



* Montagne, in Ann. d. Sc. Nat., sSr 3, vol. 18, p. 11. 

 28 * 



