TORTULA. 155 



There is a monograph of the genus by Hooker and 

 Grevillej in Brewster's Journal of Science, vol. i. 



Generic Character. — Seta terminal. Peristome single, of 

 tliirty-two spirally twisted teeth, united more or less at the hase 

 into a tubular membrane, and, with scarcely an exception, turn- 

 ing from left to right. Calyptra dimidiate. 



* Leaves thick and rigid. 



1. ToiiTULA ENEEVis, Hook. and Grevdlle. [Nerveless 

 Rigid Screw Moss.) Stems very short ; leaves few, lingu- 



late, very obtuse, concave, nerveless, rigid, the margins in- \_ 

 volute ; lid conico-acuminate, rather shorter than the oblong 

 capsule. — Eng. FLp. 43. Barbula rigida, Milll. Sijn. pt. 1. 

 p. 596. 



"Walls and clay-banks; south of England. In several 

 stations round Edinburgh, frequently associated with Gi/m- 

 nostomum ovatum. Er. October to December. Two varie- 

 ties are recorded from the south of Europe, viz. mucronu- 

 lata and hrevipila. 



2. ToRTULA BREViROSTEis, Hook. and Greville. [Short- 

 beaked Rigid Screio lloss.) Stems very short; leaves few, 

 obtuse, concave, nerveless, rigid, the margins involute; lid ^ 

 conical, scarcely beaked, half the length of the oblong cap- 

 sule.— ^;?^. FLp. 43; Mim. Sj/n. pL I. p. 597. 



