319 



affinity to Ferns; but the habit of Azolla is rather that of spme Hepaticse. 

 Marsileacese may be considered to occupy an intermediate position between 

 these tribes. Authors have not stated whether ducts are to be found in 

 Pilularia, Salvinia, and Azolla ; they are present in abundance in Marsilea, 

 where 'I have seen them ; but they are so minute as to require to be magnified 

 209 times to be distinctly observed. 



Geography. Of 20 species enumerated by writers,, all are inhabitants 

 of ditches or inundated places, in various part of the world. They do not 

 appear to be affected by climate so much as by situation, whence they have 

 been detected in various parts of Europe, Asia, Africa, and America ; chiefly, 

 however, in temperate latitudes. 



Properties. Unknown. 



Examples. § 1. MARsiLEACEiE, Ad. Brongn.in Diet. Class. 10. 196. 

 (1826), Marsilea, Pilularia. 



§ II. Salvinieje, Id. 1. c, Salvinia, Azolla. 



