DR. LINDSAY ON WEST-GREENLAND LICHENS. 363 
not appear to occur in Greenland. Possibly P. grenlandica may belong to Verrucaria 
clopima, Whlnb., which does occur in Greenland, according to Th. Fries. 
Closely resembling P. grenlandica is a saxicolous lichen sent me in 1858 by Mr. 
Carroll as an unknown Lecidea, collected by Miss Hutchins, and doubtless Irish; but no 
locality was given. The perithecia, supposed to be apothecia, are spermogonia, containing 
rod-shaped spermatia about ‘00014! long and :00005" broad—borne on simple, linear, 
filiform sterigmata—branching simply (generally bifurcating) at their base : about :0005" 
long with spermatia attached. The thallus (on which the spermogonia are scattered, 
unassociated with apothecia of any kind) is deep olive-green, crustaceous, verrucose- 
rugose, frequently becoming subpulverulent. "They are seated on the wart-like elevations 
of the thallus, at first partly immersed, their apex always protruding, latterly quite emer- 
gent. Intheiryoung, semiimmersed state they are verrucarioid, with regular or irregular 
ostioles. As they become older they gradually expand and become flattened out, so as to 
assume a lecideoid character. There is then a sort of disk with a thin margin, which is 
flexuous but entire. In this condition the perithecia frequently resemble in size and ap- 
pearance the apothecia of Lecidea chalybeia, Borr., or the spermogonia of Lecanora Ehrhar- 
tiana, Ach. *, which constitute Cliostomum corrugatum, Fr. The spermogonal walls consist 
of a deep blackish-brown cellular tissue. The spermogonia of the Irish Pyrenothea are 
probably what Leighton describes and figures as P. lithinat. By some lichenologists 
P. lithina is assigned to Verrucaria chlorotica, Ach., by others to Y. umbrina, Whinb. } 
as their spermogonia. The thallus is quite that of some saxicolous Verrucarie, but it is 
also that of certain saxicolous Lecidee, to which it is equally likely it may belong. 
V. chlorotica is represented as possessing both pycnidia and spermogonia. 
Possessing certain characters common to both P. grenlandica and P. lithina are :— 
(1.) P. sulphurea, Leight. (Ang. Lich. p. 69, pl. 29. fig. 5), which is referred by some 
lichenologists to 7. chlorotica as spermogonia ; and 
(2.) P. mollis, Leight. (Ang. Lich. p. 67, pl. 29. fig. 2.), which is a Verrucaria, accord- 
ing to Taylor, but is undoubtedly, like the other Pyrenotheæ above-mentioned, the sper- 
mogonia of some lichen, if I may judge from a specimen in my herbarium—on rock from 
the top of Carig mountain, co. Kerry. 
* Mudd, * Brit. Lichens, p. 177. t * Angiocarpous Lichens,’ p. 68, pl. 29. fig. 3. 
+ =Endocarpon lithinum, Leight., Mudd, ‘ Brit. Lichens, p. 281. 
