34 MUSCI. 



I Pterogonium. 



B. cuspidatum, the outer peristorae is of a pale yellow, while the inner 

 is reddish-brown. 



27. BARTRAMIA, Hedw. 



Seta terminal. Capsule subglobose. Peristome double ; the 

 outer of 16 teeth; the inner, a membrane divided into 16 bifid 

 segments. Calyptra dimidiate. 



1. B. pomiformis, HEDWIG. Leaves patent, subulate, strongly 

 serrated, twisted when dry, their nerve percurrent. Hedw. sp. 

 Muse. p. 164. Muse. Brit. ed. 2, p. 144, t. 23. 



On dry banks ; not uncommon. It varies in the length of its tufted 

 stems, as also of the leaves. 



2. B. ithyphylla, BRIDEL. Leaves rigid, erecto-patent, nearly 

 entire, their nerve scarcely percurrent, straight when dry. 

 Brid. Muse. v. 2, p. 1, t. 6. Muse. Brit. ed. 2, ^.145, t. 22. 



On dry banks ; in the Dargle, County Wicklow, &c. 



3. B. gracilis, FLORKE. Stems elongated ; leaves recurvo- 

 patent, lanceolate, canaliculate, serrated ; setae at length lateral. 

 Florke in Schrad. Journ. Muse. Brit. ed. '2. p.14 6. t. 23. 



On rocks in alpine districts. 



4. B. fontana, SWARTZ. Stems fastfgiate ; leaves closely im- 

 bricated, rigid, erect, broadly ovate or lanceolate, acuminated, 

 nearly plane, serrated ; setce at length lateral. Swartz in Schrad. 

 Journ. Muse. Brit. ed. 2, p. 146, t. 23. 



In wet situations ; common. This varies in the height of the stems 

 and breadth of the leaves. 



5. B. Halleriana, HEDW. K terns elongated ; leaves long sub- 

 ulate flexuose, serrulate ; setce shorter than the leaves, curved, 

 at length lateral. Hedw. St. Cr. v. 2, t. 40. Muse. Brit. ed. 2, 

 p. 147, t. 23. 



Crevices of recks in the mountains. At Colin Glen, near Belfast : 

 not common. 



6. B. arcuata, BRIDEL. Stems elongated, proliferous ; leaves 

 patent ovato-lanceolate, acuminated, serrated, striated ; setce 

 shorter than the leaves, arcuate, at length lateral ; capsule 

 smooth. Brid. Muse. v. 4, p. 139. Muse. Brit. ed. 2, p. 148, 

 t. 23. 



In wet spots in the mountains. The fruit at Powerscourt ; very 

 rare. 



b. Seta lateral. 

 * Peristome single. 



28. PTEROGONIUM, Swartz. 



Seta lateral. Peristome single, of 16, entire equidistant teeth. 

 Calyptra dimidiate. 



1. P. gracile, SWARTZ. Branches fascicled, curved; leaves 

 broadly ovate, acute, concave, their margins plane, serrulate, 



