frequently obliterate, or conceal, as they increase in size,
the areola in which they are produced. In general the
proper margin of the patellula is so incorporated with the
crust that its presence is not very decidedly evident.
This species approaches in structure to Lichen athroo-
carpus, t. 1829. We do not understand satisfactorily the
distinctions between the Acharian genera Urceolaria and
Sagedia ; and since every gradation is to be found, among
the crustaceous Lichens, between completely immersed and
completely protuberant apothecia, it is perhaps best to
refer, for the present *, to Lecidea all those species in which
the apothecium has a proper margin, whether it be or be
not surrounded by an accessory margin from the thallus,—
W. B.
* An improved generic distribution of the Lichens is expected from
Professor Fries of Lund. He is understood to have already published on
the subject; but we have not yet been able to procure a copy of his work.
