6^ 
NEW ARRANGEMENT OF 
the theca, irregularly reticulated. Peristome none. Colu- 
mella collapsed into a minute globular mass at the bottom 
of the theca. Sporiiles rather large, subsphserical, reticu- 
lated ; in one species tripartite, and punctated. 
DiFF. Chae. Seta terminal. Mouth of the theca naked. 
Operculum deciduous, entire. Calyptra mitriform, cleft ir- 
regularis/ at the hase. 
Veg. The stems of the species in this genus grow in a 
tufted manner, and are in all the species but one consider- 
ably branched. In A. eiliatum, jiliforme (Mich.), imberhe * 
(Hook. & Tayl.), repens (Hook.), and torquatum (Hook.), 
they are either decumbent or creeping ; in all the others, 
erect. Those of A. torquatum are tomentose beneath; 
caulibus ramisque inferne ubique tomento ferrugineo ob- 
sitis, stipulisque admixtis^." It is remarkable, that, in 
this genus, the leaves of most of the species are entirely 
destitute of a nerve, — >a circumstance which assuredly con- 
tributes to mark a natural limit between it and Gymno- 
stomum. A nerve, however, terminating in a piliferous 
point, is present in A. pidvinatum and subsessile ; and 
there is a percurrent one, of a brown colour, and remark- 
able strength, in A. torquatum. In regard to form, the 
leaves are usually ovate, obtuse, acuminate, and sometimes 
serrated at the apex ; but in A. torquatum, they are ligu- 
late, somewhat undulate, and " when dry, are so much 
curled as to cover the whole upper surface of the stem ; 
and if macerated for ever so great a length of time, con- 
tinue involuted in a most remarkable manner j." It is also 
• A. fdiforme ax\d imberbe, certainly do not diffex from each other; and 
we are even inclined, along with Weber and JVIohr, and Bridel, to add 
them both to A. ciliatum. 
+ Hook. Muse. Exot. t. 41. % Hook, loc. cit. 
