282 FERNS ! BRITISH AND FOREIGN. 



162. PILULAKIA, Limn. 



Plants with filiform leaves, from a creeping rhizome under 

 water. Sporangia (conceptacles) radical (at the base of the leaves 

 on the rhizome), globose, coriaceous, 2-4-celled, 2-4-valved, each 



Genus 1 62. Plant, natural size. No. 



cell containing different kinds of bodies : 1. (Antheridangia), 

 consisting of vesicles containing many minute granular spores ; 

 2. (Oophoridangia), each containing a single large spore. 



1. P. globulifera, Linn. ; Willd. Sp. PI 5, p. 535 ; Bolt. 

 Fil. t. 40 ; Sclik. Crypt, t. 173 ; Eng. Sot. t. 521. 

 Europe and Britain. 



163. ISOETES, Linn. 



Plants with awl-shaped leaves, from a thick creeping rhizome 

 under water or out of water. Sporangia (conceptacles) borne in the 



