402 
Proceedings of the Royal Irish Academy, 
Tribe 10. Brte^. 
48. Betum. Hook, et Tayl. 
Calyptra small, cuculliform, fugacious. Capsule pyriform, clavate 
or oblong, often nutant or pendulous, with a tapering neck or 
apophysis, exserted on a long footstalk. Peristome double, the 
exterior of 16 equidistant teeth, with a flexuose medial line, 
hygroscopic ; articulation close and prominent ; inner peristome 
a membrane divided into 16 processes or cilia, more or less perfect, 
and alternating with the outer teeth, ciliolae when present, one 
to three together. Leaves spreading, more or less decurrent and 
amplexicaul at base, inclined to ovate or lanceolate, costate ; areo- 
lation rather large, and rhomboidal. Inflorescence various^ 
male flowers with filiform paraphyses. 
"Wilson's arrangement of the species of this genus is followed here, 
as being easily understood, though differing from that of conti- 
nental muscologists. 
Diagnosis of Species, 
a. Leaves narrow, erect, nerve ceasing below the apex. 
* Capsule narrow, inclined. 
Inflorescence monoicous. 
Capsule slender clavate, with a long tapering 
neck, inclined horizontally ; lid conical ; 
peristome large, with the outer teeth 
incurved when dry, . . . .I.E. acumen-attjm. 
Capsule oblong, pyriform, slightly inclined, 
neck shorter than the sporangium ; pe- 
ristome wanting the inner cilia ; outer 
teeth reddish, incurved when dry, . 2. B. polymoephum. 
Stems short ; leaves erect, lanceolate-acumi- 
nate, serrated ; capsule elongate, clavate, 
inclined ; peristome with inner cilia more 
or less complete, . . . . 3. B. elongatum. 
Inflorescence synoicous or dioicous. 
Stems simple; leaves lanceolate, erect, rigid 
serrulate, nerve not quite percurrent ; 
capsule oblong-pyriform, cernuous, lid 
rather apiculate, 4. B, cetjdum. 
