3G6 Proceedings of the Royal Irish Academy, 
27. PoTTiA. Ehrh. 
Calyptra ciiciilliform, smooth or rough on the apex. Capsule either 
exerted or immersed, obovate-truncate or oval oblong. Peristome 
none. Leaves mostly entire, ovate-oblong or spathulate ; nerve 
frequently excurrent into a mucro; areolation loose or dense, the 
cellules often of a rectangular or quadrate form, enlarged at the 
base. Small annual or biennial mosses growing chiefly on the 
ground. 
With this genus, Mr. Mitten unites that of Anacalypta, of Eohling, 
and in " Journal of Botany," vol. ix„ for January, 1871, ar- 
ranges the species in the following manner : — 
Diagnosis of Species, 
a Leaves with accessory lamellce on the 
nerve, . . . . . .LP. cavifolia. 
aa Leaves without accessory lamcllte. 
h Calyptra scabrous. 
Leaves obtuse, . . . . . 2. P. "Wilsoni. 
Leaves acute, . . . . . 3. P. Starkeana. 
hh Calyptra smooth. 
c Leaves serrulate towards the apex. 
!N'erve not excurrent, . . . . 4. P. Heimii. 
I^erve excurrent, 5. P. lanceolata. 
cc Leaves in 5 rows, smooth. 
Capsule turbinate, . . . . 6. P. trtjncata. 
ccc Leaves in 8 rows, rough. 
JTerve excurrent into a long point, . . 7. P. ceinita. 
1. P. cavifolia (Ehrh.). Beitrage — Bryol. Europ., vol. ii., Monogr., 
p. 7, tab. 118. Rabenhor., Bryothec. Europ., jS'o. 724. Gym- 
nostomum ovatum (Hedw.), Engl. Bot., tab. 1889. Turner, 
Muscol. Hib., p. 9, Muscol. Brit., p. 21. Bryol. Brit., p. 92, 
tab. 7. Barbula cavifolia, iSchimp. Synop. Muscor., p. 734. 
Hab- On the tops of walls built of mud, and by way sides. Very 
common in the neighbourhood of Dublin. Near Cork, Tayl. . 
in EL Hib. 
