450 INTRODUCTION TO CRTPTOGAMIC BOTANY. 



to retain the tribe. It consists of but two genera of very diffe- 

 rent babits. Monoclea has the habit of Anthoceros, having a 

 horizontal frond ; Calohryum, has a creeping primary stem, 

 with erect branches, clothed with obliquely obovate, entire, 

 vertical leaves. The sporangium is about two lines long, 

 splitting on one side only. 



3. Aneuki^, Nees, Endl. 



Fruit marginal, ventral ; involucre lobed or torn ; peri- 

 anth none ; archegonium adnate with the torus ; sporangium 

 oval or oblong, four-valved ; elaters unispiral, attached to the 

 tips of the valves ; frond fleshy, palmate, or pinnatifid, desti- 

 tute of any nerve. 



493. We begin here the frondose four-valved Jungertnan- 

 nicB, distinguished by the jagged margin, and the nerveless 

 fronds. Their favourite place of growth is the margin of ponds, 

 the base of overhanging rocks, or other situations, where they do 

 not receive the direct light of the sun. In such situations two 

 or three species are extremely common. The tribe contains 

 but one genus, Aneura, almost equally distributed between the 

 temperate regions and the tropics ; and of the European 

 species, two or three are almost cosmopolitan. In all proba- 

 bility the species are far too greatly multiplied, for, as regards 

 size, and the outline of the frond, they vary extremely. The 

 elaters remain for a long time attached to the tips of the valves, 

 which are often ornamented with a pencilled appendage arising 

 from the inner membrane. 



4. Metzgeri^, Nees, Endl. 



Fruit ventral, springing from the midrib ; involucre mono- 

 phyllous ; perianth none ; archegonium rather thick ; sporan- 

 gium ovate ; elaters unispiral, attached to the tips of the 

 valves ; fronds ribbed, forked. 



494. This tribe consists, like the last, of but a single genus, 

 and is distinguished mainly by the presence of a midrib in the 

 frond, and the forked division. They grow more frequently on 

 trees, rarely on the ground. Of the two British species, M. 

 fuTcata, a very variable plant, is perfectly cosmopolite, occur- 

 <ring in both hot and cold regions in either hemisphere, and M. 

 puhesceyis (remarkable for its pubescent frond) is found in the 



