INTRODUCTION. 1 7 



Autoicous. — When the male and female sexual 

 organs of the same plant are nevertheless found in 

 a separate inflorescence. 



Heteroicous. — When synoicous (or paroicous) 

 and autoicous flowers are found on the same plant. 



Dioicous. — When the male and female inflores- 

 cences are found on different individuals. 



Polyoicous. — When the male and female sexual 

 organs occur at one time on the same plant, and 

 at another time on a different plant. 



Classification. 



It has already been intimated that, as at present 

 understood, the Muscinece include with the Bog- 

 mosses and the true mosses, the Hepatics also, as 

 one of the primary divisions of the Higher Crypto- 

 gamia. We have pointed out the distinctions 

 between the several orders of Hepaticae, and no- 

 thing remains but to indicate the subsidiary div- 

 isions, chiefly in so far as they relate to the Junger- 

 manniacece. Sixty years ago, and for some time 

 after, all the species were associated under the one 

 genus Jungermannia, whether foliose or frondose ; 

 and, notwithstanding Gray's proposition of a num- 

 ber of new genera, in 182 1, these were ignored in 

 1833, and it was not until some time after the pub- 

 lication of Gottsche and Lindenberg's Synopsis in 

 1844 that more than one genus of the Jungermau- 

 niacece was recognized in this country. The first 

 departure was by Dr. Spruce in 1850, but it was 

 not until 1865 that Mr. W. Carruthers called special 



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