PDF - CES (IISc)

FAMILIES AND GENERA 331
which grows out from all sides and meets across the opening. The overlying
layers, with gonidia, follow more slowly, but they also in time become
continuous, so that the "erose" character persists only near the periphery.
This forward growth of the lower thallus occurs in other species, though to
a much less marked degree.
There is abundant detritus formation in this family; the outer layers of
the cortex are continually being sloughed, the dead tissues lying on the
upper surface as a dark gelatinous layer, continuous or in small patches.
On the under surface the cast-off cortex gathers into a loose confused mass
of dead tissues.
Asci 8-spored.
Spores mostly simple (disc gyrose) i. Gyrophora Ach.
Spores i-septate 2. *Dermatiscum Nyl.
Asci i-2-spored.
Spores muriform 3. Umbilicaria Hoffrn.
XXXV. ACAROSPORACEAE
Thallus foliose, squamulose or crustaceous, sometimes scarcely developed.
Algal cells Protococcaceae.
Into this family Zahlbruckner has gathered the genera in which the
asci are many-spored, as he considers that a character of great importance
in determining relationship, but he has in doing so overlooked other very
great differences. The fruit-bodies are round and completely enclosed in
a thalline wall in Thelocarpon, which has however no perithecial wall. They
have a proper margin only (lecideine) in Biatorella, and a thalline margin
(lecanorine) in the remaining genera. In Acarospora the apothecia are sunk
in the thallus. Stirton's genus Cryptothecia^ is allied to Tfielocarpon
in the
fruit-formation, but the basal thallus is well developed and the spores are
few in number and variously divided.
Thallus none.
Apothecia (or perithecia) in thalline warts i. Thelocarpon Nyl.
Thallus crustaceous.
Apothecia lecideine ; spores simple 2. Biatorella Th. Fr.
Apothecia lecanorine ; spores septate 3.
*Maronea Massal.
Thallus of small squamules 4. Acarospora Massal.
Thallus almost foliose, attached centrally 5. *Glypholecia Nyl.
XXXVI. EPHEBACEAE
A family of very simple structure either filamentous, foliose or crustaceous.
The algal cells which give a dark colour to the thallus are Stigonema or
Scytonema, members of the blue-green Myxophyceae, and consist of minute
simple or branched filaments single cell-rows in Scytonema, compound in
Stigonema.
1 Stirton 1877, p. 164.