78 DICRANACEiE. 



Capsule on a long seta, oblong or cylindrical, cernuous, with a 

 straight or curved neck, its own length or longer. Peristome 

 teeth 16 (rarely almost wanting), subentire, or more or less 

 deeply divided into two unequal, papillose segments, which are 

 usually somewhat united above, here and there perforate. 



Besides the present one, the section includes the genus 

 Bruchia, with cleistocarpous, long-necked capsules. 



1. Trematodon ambiguus Hornsch. (Dicranum ambiguum 

 Hedw.) (Tab. XIV. L.). 



Densely tufted, pale green or brownish. Stems short, slightly 

 branched. Leaves erecto-patent, flexuose, from an ovate-oblong 

 concave base suddenly subulate-setaceous, channelled, faintly 

 denticulate at the extreme apex. Nerve narrow, reaching to 

 apex. Cells long, lax, hexagonal-rectangular and empty at base, 

 quickly narrowing above and becoming irregularly quadrate in the 

 subula, where they form a very narrow margin, and are small, 

 chlorophyllose and obscure, becoming still more so at the apex 

 where they are hardly distinct from the nerve, which is not, how- 

 ever, strictly excurrent, or only rarely very slightly so. 

 Pericha^tial bracts much larger, more gradually acuminate. Seta 

 variable in length in the same tuft, y z -i% inches long, flexuose, 

 straw-coloured, shining ; capsule (with the neck) clavate, arcuate, 

 bright orange red ; the capsule itself oblong or shortly cylindric, 

 with a long neck equal to itself, which narrows gradually into 

 the seta on the outer, convex side, or back of the fruit, but at the 

 base on the front or inner side ceases abruptly and gives the 

 appearance of a struma. Annulus broad ; lid subulate-rostrate ; 

 teeth confluent at base on a short membrane, irregularly perforated 

 and divided, sometimes cleft to base. Autoicous ; male flower on 

 a basal branch, terminal. Spores large, granulose. 



Hab. Bare turfy places in subalpine districts. Extremely rare. Perthshire. 

 Fr. late summer. 



Only a single tuft of this beautiful moss has been found in Britain, by Braithwaite 

 and Crombie, in 1883, at the base of Schiehallion. It is not very rare on the 

 continent, and is frequent in N. America. Two other species are found in Europe, 

 distinguished chiefly by the relative length and the form of the neck of the fruit. The 

 long inflated neck gives the fruit a very peculiar appearance, and is totally different 

 from anything else in this order, and indeed more resembles that of some species of 

 Meesia'or Webera, but only superficially. The inequality of the base of the neck is 

 not very obvious until the fruit is ripe, but is of importance in distinguishing T. 

 ambiguus from other species of the genus. 



