THE GENERA OF MOSSES» 
147 
DiFF. Char. The tlieca falls akmg with the seta; ca- 
lyptra large and permanent. 
Veg. In one species the stems are scarcely more than 
three-fourths of an inch in height, but in the other they 
reach from two to three inches : they are either simple or 
branched, and so closely matted together (at least in V. 
nivalis), that it is extremely difficult to separate a complete 
plant from the mass. The leaves are imbricated, erccto- 
patent, of a yellowish-green colour, ovate, more or less con- 
cave, scarcely acuminate in one, and considerably so in the 
other species, very entire, embracing the stem at their base, 
with a strong brown nerve reaching to the apex ; their re- 
ticulation is large, and nearly rectangular ; the perichaetial 
leaves are much more acuminated, tender in their structure, 
but equally furnished with a strong nerve. 
Obs. Few plants are more remarkable than those which 
form the present genus. Their closest affinity is to Phas- 
cum, especially P. hryoides ; but the persistent calyptra of 
Voitia, and what is of much greater importance, the theca, 
deciduous only along its seta, must for ever keep them dis- 
tinct ; while, on the other hand, the adnate operculum is 
sufficient to separate them from all other mosses that may 
resemble them in habit. Among those with which they 
might at first be confounded, are, the EncalypteE and 
Splachna, and even some of the Brya. 
Horns CHUCH, in his " Commentatio de Voitia et Systy- 
lio" (from which, by changing the terms, we have borrowed 
nearly the whole of our description of the fructification), 
describes the theca of his species — " ovata in acumen sub- 
obliquum, truncatulum, pellucidulum attenuata,"*"* while he 
denies it to possess an operculum ; so far we do not agree 
with him, and have accordingly denominated the termina- 
K 2 
