INTRODUCTION TO CRYPTOGAMIC BOTANY. 461 



confined to the lower in the same species. The amphigastria 

 also differ much in size, number, and arrangement. In fact, 

 the characters are so variable that the student must be pre- 

 pared for great differences, and must not suppose that slight 

 distinctions are sufficient for the proposition of new species. 

 One or two incubous Jungermannice occur in amber.* These 

 are, I believe, the only certain traces of such plants in fossil 

 remains. 



IV. Musci, Juss. 



Bryaceye, Lindl. (exclusis Andr<xaceis). 



Sporangia valveless, or very rarely valvate with the tips of the 

 valves free or adherent, opening for the most part by a definite 

 horizontal fissure, the mouth of which is naked or fringed with 

 various appendages, mostly definite in number. Elaters, none. 

 Calyptra parting at the base, and carried up by the pedun- 

 cle, or very rarely ruptured in the midst. Leaves simple, 

 mostly regular ; cells sometimes containing a spiral thread. 

 Fruit often furnished with true stomates. Antheridia on the 

 same or on diffeirent plants from the sporangia. 



507. The vast mass of Cryptogams known under the name 

 of mosses, is with few exceptions at once distinguishable to the 

 naked eye from Hepaticce, even in the absence of fruit. For 

 the leaves are not only regular in outline, but there is far more 

 variety in their spiral arrangement, and even in those cases 

 where they are distichous and filmy, there is a peculiar inde- 

 finable aspect about them which is seldom deceptive. If the 

 determination is easy at first sight in the absence of fruit, the 

 facility is greatly increased when this is present. In one small 

 tribe alone is there any approach to the valvate sporangia, 

 which have been with such rare exceptions present in Hepa- 

 ticce. Moreover, in one case alone of Marchantiaceoi have we 

 seen anything in the shape of peristomal appendages to the 

 sporangia, with the exception of the elaters, which belong to 

 a totally different category ; whereas in mosses, except in a 

 few simple cases, they are universal. Though occasionally, 



* See Gseppert, Organisclie Reste im Berusteiu. 



