INTRODUCTION TO CRYPTOGAMIC BOTANY. 483 



532. The principal distinguishing feature of this small tribe, 

 which consists but of two genera, Hydropogon, founded on 

 the old Grimmia fontinaloides, and Cryptangium, seems 

 to consist in the nerveless leaves. In most of the aquatic 

 mosses there is a tendency in the sporangia to become im- 

 mersed in the perichffitial leaves, but in none is this character 

 so strong as in Hydropogon. H. fontinaloides appears to be 

 common on the Orinoco, near San Fernando, as it is called 

 Barba de palo by the natives. The main stems are quite bare 

 of leaves ; the branchlets, however, are beset with densely 

 imbricated, nerveless, oblong, serrated leaves, which gradually 

 pass into more pointed perichretial leaves, concealing the 

 minute, oblong, erect, nearly sessile, sporangium. The peristome 

 consists of sixteen obtuse teeth more or less jagged. In the 

 other genus, from Cayenne, the operculum is acuminate instead 

 of umbonate, and the peristome is altogether wanting. 



9. Encalyptei, Br. & Sc, Mont 



Sporangium straight, cylindrical, even or striate, covered by 

 the large funnel-shaped persistent calyptra ; peristome none, 

 single or double. 



533. Though the characters of the peristome vary so greatly 

 in the species of which this tribe is formed, they are so con- 

 nected by general habit, and by the large cylindrico-campanu- 

 late persistent calyptra, that there can be no doubt about their 

 affinity. Their habit is that of some of the larger species of 

 Tortula, and they grow on the tops of walls, or on stones and 

 rocks, especially those which are calcareous, of which they 

 constitute a chief ornament when abundant. In li. commu- 

 tata the peristome is wholly absent ; in E. vulgaris it is very 

 fugacious ; in JS. ciliata it is persistent, consisting of sixteen 

 teeth ; in E. streptocarpa it is double, the outer consisting of 

 sixteen teeth, the inner of as many processes, alternating with 

 the outer. The species are almost exclusively confined to 

 Europe or North America, but there are traces of the genus 

 in Chiloe, Peru, and Kumaon. 



10. Hedwigiacei, Br. & Sc, Mont. 



Sporangium globose or oblong, more or less immersed ; 

 31 * 



