Moore— the Mosses of Ireland. 
371 
31. DiDYMODOisr. Br. et Schimp. 
Calyptra cleft at the side. Capsule oblong or subcylindrical, annu- 
late, pedicellate. Peristome single, of 1 6 teeth, which are entire or 
slightly bifid, very shortly joined at the base, but mostly free, and 
approaching in pairs, sometimes appearing as 32, fugacious. Leaves 
with dot-like areolation, and frequently opaque with chlorophyll, 
basal cellules longer and narrower, more pellucid. 
So little difference exists between this genus and Trichostomum, 
that the species described under it by authors have been re- 
ferred to the latter by Mitten, Lindberg, and some others. De 
I^otaris has however retained it in his great work on the 
mosses of Italy, " Epilogo della Briologia Italiana," 1869; 
and as the genus Didymodon is so familiar to British Bryo- 
logists, it has been thought better to let it remain on our 
list. 
Diagnosis of Species. 
A. Inflorescence dioicous. 
Leaves long, broadly subulate, spreading; 
margin slightly undulated ; crisped when 
dry, .1. D. CTLiN-DEicus. 
Leaves oblong, ligulate, apiculate, flexuose 
and crisped when dry, . . . 2. D. flexifolius. 
Leaves subsquarrose, recurved and serrated at 
margin ; crisped when dry, . . . 3. D. recurvifolius. 
Leaves acutely ovate ; margin revolute, nerve 
reaching the apex ; areolation dot-like, 4. D. luridus. 
B. Inflorescence monoicous. 
Leaves .spreading and recurved, oblong- 
lanceolate, 5. D. RTJBELLUS. 
1. D. cylindricus{'^Y. ei^Qhim^.). Bryol. Europ., vol. ii. Monogr., 
p. 5, tab. 187. Schimp., 8ynops. Muscor., p 132. Bryol. Brit., 
p. 108, tab. 33. Trichostomum tenuirostre, Lindberg, Trichost. 
Europ., p. 15. "Weissia tenuirostris, Muscol. Brit., p. 83, tab. 
3. 
Hab. On wet banks and rocks near waterfalls, &c. At the Water- 
fall, Powerscourt, Wicklow ; also by streams among the Dub- 
lin Mountains. Very frequent about Killarney ; Connemara ; 
Benbulben, Sligo ; in "The Glens," Co. Antrim, &c. 
