ANCECTANGIUM. 233 



47. ANCECTANGIUM Schwgr. 



Tall, densely matted plants ; leaves lanceolate, papillose, 

 areolation small, opaque. Perichsetia on the side of the stem ; 

 seta long. Calyptra smooth, cucullate. Capsule smooth, ovate ; 

 peristome none. 



A very curious genus, remarkable for the lateral fruit, a 

 character which has given rise to much variety of opinion as to its 

 true position ; it is clear, however, that its natural place is among 

 the acrocarpous mosses rather than with the true pleurocarps, and 

 among these its affinity appears closest with Zygodon, although it 

 very closely resembles some species of the genus Weisia. 



Besides the single British species, several others are known, 

 one of which, A. Hornschuchianum (now placed by Lindberg 

 in a separate genus), was described as British by Wilson in 

 the Bryologia Britannica, but the plant referred to proved— as 

 Wilson suspected — distinct, and is the species described in the 

 present work as Trickostomum hibernicum. 



1. Ancectangium compactum Schwgr. (Gymnostomum com- 



pactum Schleich. ; Pleurozygodon sestivus Lindb., Braithw. 



Br. M. Fl.) (Tab. XXXIII. E.). 



In very dense deep soft tufts, pale vivid green on the surface, 

 bright brown below. Stems 1-4 inches high, very slender, closely 

 compacted and interwoven with reddish tomentum. Leaves 

 small, lanceolate or linear-lanceolate, acuminate and acute, 

 strongly carinate, erecto-patent ; when dry closely incurved and 

 slightly twisted ; margin plane, minutely crenulate with papillae, 

 towards apex entire or sometimes indistinctly waved or irregular; 

 nerve very prominent at back, green, vanishing at apex ; areola- 

 tion very obscure, papillose, quadrate-hexagonal, small, opaque, 

 at base shortly rectangular, paler, more pellucid. Perichastial 

 bracts sub-sheathing, shining, not papillose ; seta about |-inch 

 long, pale. Capsule elliptical-oblong, with a more or less distinct 

 neck, pale brown with a shining reddish mouth, darker when old, 

 rather glossy, thin-walled. Lid with a very long oblique subulate 

 beak. Peristome wanting. Dioicous. 



Var. /?. pellucidum (Ancect. pellucidum Wils.). More 

 robust, with larger, broader, less carinate leaves, more flaccid 

 and less rigidly incurved when dry ; areolation larger, much 

 more distinct and pellucid, smoother, nerve rather narrower. 



Hab. Shady siliceous rocks on mountains, not uncommon ; most frequently 

 barren. The var. near Inverary ( Wilson, 183b) ; Meall nan Tarmachan, Perthshire 

 (Jameson, 1893). Fr. summer and autumn. 



