Didymodon.^ APLOPERISTOMI. 113 



appearance of our plant except in having the branches some- 

 what shorter and more tumid. The "folia octofaria oblique 

 imbricata" may often be seen as distinctly upon our specimens 

 of L. sciuroides as upon jL. Mbrensis. 



The fructification is very scarce in this country ; fine speci- 

 mens of it have been gathered by Mr. Lyell in the New Forest. 



XXII. DIDYMODON. 



GEN. CHAR. Fruitstalks terminal; Peristome single, of 16 

 or 32 teeth approaching in pairs, or united at the base ; 

 Calyptra dimidiate. (TAB. II.) 



In natural habit the plants of this genus are allied on the 

 one hand to the Weissice, and on the other to the Dicrana. 

 With the former, two species are liable to be confounded, viz. 

 Didymodon inclinatum, and D. heteromallum, each of which has 

 but 16 teeth, and their approximation in pairs is with difficulty 

 discoverable. In D. nervosum and purpureum, besides being united 

 in pairs at the base, we find them connected in various parts of 

 their length by transverse bars ; and in D. nervosum their direc- 

 tion appears not erect but oblique. The teeth of D. trifarium 

 approximate very closely in pairs ; those of D. capillaceum and 

 heteromallum less so ; moreover, in the latter each tooth has fre- 

 quently a longitudinal cleft down its centre. 



* Capsules inclined. 



1. D. purpureum ; stems scarcely branched, leaves lanceolate acu- 

 minate carinated their margins recurved entire, capsule ovato- 

 cylindraceous oblique substrumose farrowed when dry, lid 

 conical. (TAB. XX.) 



Didymodon purpureum. Hooker and Tayl. Muse. Brit. ed. 1. p. 65. 

 Hook. Fl. Scot. P. II. p. 135. Am. Disp. Muse. p. 35. Hobson, 

 Brit. Mosses, v. 1. n. 48. Drummond, Muse. Scot. v. 2. n. 49. 



Dicranum purpureum. Hedtv. Sp. Muse. t. 36. Turn. Muse. Hib. 

 p. 72. Smith, Fl. Brit. p. 1217. Engl Bot. t. 2262. Moug. et Nestl. 

 n. 24. Schwaegr. Suppl. v. 1. p. 183. Fvnck, Deutschl. Moose, t. 21. 

 n. 25. JBrid. Meth. p. 69. 



H 



