496 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



various intermediate stages between a vertical and horizontal 

 insertion, and are sometimes perfectly free ; while at others 

 they are united, and have in consequence a Jungermannioid 

 aspect. The name was originally given on account of a 

 supposed tendency in the lid to become fissured ; but it is as 

 entire as in other mosses. The lower half of the vaginula is 

 leafy, as in most Pleurocarpous mosses. The spores in young 

 sporangia radiate from the columella, as they do in Splachna. 

 It seems to be confined to the northern hemisphere, but is far 

 from being generally diffused anywhere. 



IV. Cladocarpi, Mont. 

 Sporangia seated at the tips of very short lateral branches. 



552. Having separated the Sphagnei from the Acrocarpous 

 mosses, on account of their peculiar characters and intimate 

 relation with the Schistocarpi, we have, after the few excep- 

 tional cases afforded by such genera as Ginclidotus, a group 

 connecting plainly the Acrocarpous with the Pleurocarpous 

 mosses. They are, indeed, few in number ; but as they cannot 

 conveniently be associated with either, it is well to place them 

 in a distinct division. 



1. MlELICHOFERIEI, Br. & Sc, Motit. 



Vivacious, biaxile, cladocarpous ; sporangium straight ; peri- 

 stome simple or double, with or without an apophysis. 



553. These mosses are closely related to Bryei, but differ 

 greatly in their double axis of growth. The vaginula is dis- 

 tinctly formed as in the Acrocarpous mosses, but the fertile 

 branch is truly lateral, putting forth rootlets at its base, and 

 closely resembling the perichajtium of the Pleurocarpi. In 

 one or two instances, however, it is difficult to say whether 

 the portion which bears the sporangium is the main axis, with 

 an elongated barren branch growing beneath it, or whether 

 the latter is in reality primary. In Mielichoferia the spo- 

 rangium is pyriform, or clavate with a large annulus, and sim- 

 ple peristome of sixteen teeth confluent below, and resembling 

 that of Anacalypta. Pleurogonium has eight pairs of broad 

 short teeth. DiplostichuTYi has sixteen teeth united at the 

 base, as in Mielichoferia, but the leaves are distichous. The 



