170 NEW LIGHENS. 
of the thallus are of a smoke grey, the younger paler, and 
snow-white beneath the edges. The segments are not so 
dilated as in P. tenella, Ach., and there are no soredia | 
present. | 
24. P. leiocarpa, Tayl.; thallo orbiculari, cinereo-virescentt, — 
rugoso, sublacunoso, lobis periphericis tenuibus, rotan- - 
datis, crenulatis, subtus albido-cinereis ; gemmis granulatis 
demum cylindricis ; apotheciis concavis, nudis, disco 
pallide castaneo, margine incurvo demum crenulato. 
Has. United States; Greene, Hook. herb.—Thallus 3-4 
inches wide, coarsely wrinkled, the intervals again minutely 
wrinkled, whitish-ash coloured when dry, greenish when 
wetted: the inferior surface is whitish brown. Differs 
from both P. sazatilis, Ach., and P. aleurites, Ach., by the 
absence of the dense black trieze beneath, and remarkably 
: by the naked apothecia, on the margins and bacis of 
= which the buds do not appear. e 
25. p. dimaformis, Tayl.; thallo sanie cinereo, ceespitoso, à 
adscendente, lineari, dichotomo, apicibus "acuminatis, 3 
subtus canaliculato, atro, gemmis granulatis confertis- tenté : 
atque scaberrimo. . 
Has. Chiloe; Cuming, Hook. herb. — Thalli 28 inches : 
long. The ‘buds at first appear as black points, but soon - 
become whitish elevated granules: short black tricæ t 
. very sparingly on the inferior surface. —— 
26. P. leucothriz, Tayl. ; thallo orbiculari, albido depresso 
- lineari, multifido-laciniato, laciniis minutis, approximatis, 
_crenulatis, breviter albo-ciliatis, subtus albis, gemmis 
. coloribus, granulatis ; apotheciis | marginalibus, planius: 
_ lis, disco rufescenti, margine demum - erénulaté, extus 
— fibrillos albidos demittentibus. — fé E 
Has. On bark ; St. Vincent's; Rev. L. Guilding, Hook. er? 
. —Patches 2-3 inches in diet; exteriorly linear à 
_ radiating ; at the centre the lobes are shorter : : buds in 
< white, round grains, Api seni n 
asin P: aiina Achis but wi species has the 
