2?f>8
VERRUCARIA submersa.
Rivulet Verrue aria.
CRYPTOGAMIA Lichenes.
G e n . C h a r . Tubercles of a different substance from
the thallus, simple, convex, not expanding, but
furnished with a central pore, and inclosing a
somewhat gelatinous nucleus.
S p e c . C h a r . Crust tartareous, somewhat gelatinous,
thin, continuous ; when young green and diaphanous
; at length opake and black; pale
browrn when dry. Tubercles immersed, dimidiate,
depressed, the central papilla only emerging.
O n stones under water in clear shallow streamlets and
springs, in somewhat mountainous districts. It occurs in
Hind Head, and near Abinger, Surrey, above Rundhurst
at the foot of Black Down, in Harting Coomb, and at Ed-
burton, Sussex ; and Mr. Joseph Woods has communicated
specimens from the North of England.
Crust at first circular, but soon confluent and irregularly
effused; sap-green and diaphanous, so as to show
the immersed tubercles, in young specimens and in the
thin parts of older ones, of which the thicker parts are
black ; surface continuous, very minutely rugose or wavy.
Tubercles numerous, depressed, their base often effused,
and not unfrequently so widely as to become confluent,
and form an interrupted black substratum to the crust;
their surface mostly covered entirely, the crust rising in a
little prominence above each of them, and occasionally
pierced by the minute central papilla ; nucleus pale, not