476 INTRODUCTION TO CRYPTOGAMIC BOTANY. 



United States; but, with one or two exceptions only, the 

 species of the southern hemisphere are peculiar to it. Hong 

 Kong produces one which is allied to P. crispum. The 

 tribe, on the whole, belongs certainly to temperate regions ; 

 it is possible that the one or two European forms which occur 

 at the Cape may have been introduced by cultivation. It 

 still possesses some peculiar forms, and a distinct species of 

 Bruchia. 



2. Weissiei, Mont. (Weissiacei, Bt. & Sc). 



Sporangium erect, equal. Peristome wanting, or consisting 

 of 16 teeth, often united at the base. Tissue of leaves 

 compact. Calyptra dimidiate. 



526. A large number of genera are referred to this tribe, 

 which contains numerous but often very obscure species. 

 GymnostomuTii has the aperture naked, and sometimes much 

 contracted. In some of those species which are referred to 

 Hymenostomum, the top of the sporangium remains attached 

 to the apex of the columella, thus forming a closed sac at the 

 period of maturity. Weissia differs from Gymnostomum. 

 merely in the presence of a peristome, consisting of sixteen 

 teeth. These are sometimes bifid at the apex, and the genus 

 is thus confluent with DicTanum. Rhabdoweissia has a 

 striated sporangium ; in Brachyodus the teeth are very short 

 and truncate ; in Seligeria the sporangium is pyriform, with a 

 large rostrate lid, and a cucullate calyptra, and from this 

 Anodus differs only in the absence of a peristome. These are 

 the principal British genera, but many others occur, of which 

 I cannot speak particularly. They are found in both hemi- 

 spheres, and some species, as Weissia controversa, acuta, &c., 

 are common to both, though each has also its own species. 

 Eucladon and LopJdodon, for example, are antarctic genera. 

 The latter has the teeth approximated in pairs. Eucamp- 

 todon perichcdialis, a Chili species, has already been noticed 

 (Fig. 99, e) for its curious spores. A few species occur in hot 

 climates, as, for example, Gymnostomum lamprocarpum in 

 Dominica ; Weissia macrorhyncha and Miqueliana, in Java. 

 Montagne includes Didymodon, and other genera which 

 have cleft teeth: but these come better under Dicranei or 



