120 
It. is generally encrusting, but sometimes it rises into 
froml-like prolongations, with a layer of cells on either side, 
separated from each other by a central cavity ; the sides 
however are generally in contact, and afford each other 
mutual support. 
M. UNICORNIS. Encrusting, calcareous; cells oval, with 
a short stout spine on the lateral or distal rim. 
Flastra unicornis, Fleming’s Brit. An., p. 536. 
llab. On stones, not uncommon. Polperro. Goran, &o- 
This encrusting calcareous species occurs in patches of 
about three-fourths of an inch in diameter. The cells are 
oval, with stout calcareous rims, and are arranged in circular 
rows. The margins of the oral apertures, are embossed an 
marked with three or four circular orifices. The aperture* 
are circular and armed with a stout spine on the distal o f 
lateral margins. 
M. PEACHII. Encrusting; cells radiating; aperture* 
oval, unarmed, with two punctures at each extremity. 
Flustra Peacliii, 9th Report of the Cornwall Polytechnic 
Society, p. 81. . 
ITnb. On dead muscle and oyster shells in the Falmouth 
and Fowey rivers; off the Deadman point; common. 
Encrusting, membrano-calcareous ; cells ovoid, bavins 
their longest diameter in the axis of growth, and at eaC j 
extremity two minute punctures; the apertures even a u 
unarmed. The cells which have a radiating distribute ' 
appear somewhat confused from their radiating from so naan; 
points and intermingling with each other. y 
This species was first found by Mr. Peach in the 
river; since then in company with him I have fouI r ,,, 
abundantly encrusting almost every shell dredged up, 1 
Mixtow to the mouth of the river. I have since found \ 
deep water nine leagues south of the Deadman and in J 
other parts of the British Channel. It is now acknowletfc 
to be a good species and 1 therefore give it the name o 
discoverer. 
ESCHARIDiE. 
Polypidoms calcareous, or membrano-calcareous, v 
variable iti form; composed of cells usually disposed w 1 ct , 
cuux ; the cells oblong, pentagonal or hexagonal, coj.^ 
immersed, horizontal to the plane ot axis, with • s cJ ~ 
or lateral apertures, which are usually covered w 
cula. Polypes aseidian. 
