Grimmiace^.] 6o Zygodon. 



rarely none, the teeth resembling those of Orthotrichum. Calyptra 

 smooth, cucullate. Inhabiting trees and rocks.— Der. ?«yos a yoke, 

 oSovs a tooth. 



Between 60 and 70 species of this genus have been described, about half 

 of them being natives of S. America. The peristome agrees in structure 

 with that of Orthotrichum, the lid differing in being obliquely rostrate, and the 

 calyptra cucullate. 



Clavis to the Species. 



Nerve excurrent in a mucro. Slirtont. 



vanishing below point. 



Leaves entire, plants rather short. 



Peristome none. viridissimus. 



present. 



Autoicous, in dense tufts with pale radicles. Forsteri. 



Dioicous, in loose tufts with red radicles. coiioideus. 



Leaves denticulate at apex, plants tall. gracilis. 



I. ZYGODON STIRTONI, Schimp. 



Dioicous ; leaves dense, erecto-patent, elongate lanceolate, the 

 wings often unequal at apex ; nerve thick, prominent at back, excurrent 

 in a smooth-pointed mucro ; cells at base ovali-rectangular smooth, 

 above rounded, papillose. Caps, subglobose. (T. LR', B.) 



S\s.— Zygodon huiinlis Hunt MSS. 1867. 



Zygodon Stirtoni Schimp. MSS. Stirton in Trans, hot. soc. Edin. xi, 75 {1871). HusN. 

 Muse. gall. 148, t. 42 (1887). 



Zygodon aristatus Lindb. Act. soc. so. fenn. x, 542 (1875). 



Dioicous ; in short dense tufts, dull yellow-green above, fuscous and 

 radiculose at base, dichotomous. Leaves dense, erecto-patent, straight, 

 elongato-lanceolate, wings often terminating unequally at apex, the 

 margin crenulate with minute papillae ; nerve yellow, thick, rounded and 

 very prominent at back, excurrent as a very thick, subterete pungent 

 fragile awn ; cells strongly incrassate, basal ovali-rectang. or quadrate, 

 smooth, the rest rounded, chlorophyllose, each with several minute acute 

 papillae on the surface. Perich. bracts like the leaves but with a shorter 

 awn, and the cells in the lower half laxer and more elongated ; caps, on 

 a yellowish elongated seta, erect, leptodermous, subglobose-pyriform 

 with a small mouth, gymnostomous, faintly striate when dry ; Hd 

 rostrate. 



Hab. — Rocks and hmestone walls, especially near the sea. Fr. rare, 4, 



Roadside near Barmouth c. fr. {Wilson 1863) ! Coast at Elie, Fife, c.fr. {Howie 1864) ! 1 

 Buxton {Hunt 1867) ! I Arbroath and Troup head, Forfar {Fergnsson 1864) ! ! Menmuir, 

 c. fr. {Anderson). Bowling and Campsie {Stirton 1865). Ben Lawers and Killin 

 (Stirton 1867). Limestone wall at Plymouth {Holmes 1867) ! ! Cromaglown and 



