113 
LEPRALIA. Jolmston. 
Generic Character: Polypidom calcareous, or membrane- 
calcareous, adnate, crustaceous, spreading circularly, 
formed of a layer of urceolale cells in juxtaposition, and 
arranged in a quincunx ; aperture terminal, often covered 
with an operculum. Polypes ascidian. 
k. PEDILOSTOMA. Encrusting, calcareous ; cells ovoid, 
alternate, frosted, with a stout spine on the upper surface ; 
apertures terminal, round, unarmed. PI. xxii., fig. 14. 
Hah. On stones about one mile from the shore, common ; 
^olperro. Goran. Mr. Peach. Falmouth. 
This, with several of the following species, are here des- 
Cr *bed for the first time. They have long lain by me, but as 
they C ould not be satisfactorily refered to any described 
species, they were omitted in the Report of the Cornwall 
Polytechnic Society, till their specific differences could be 
decided on. Having been supplied with a collection from 
v arious localities by my friend Mr. Peach, and having com- 
pared them with those in my own collection, they prove to 
l, 6 distinct; and the one now under consideration has been 
Earned pedilostoma by Mr. Hassal. 
It is very commonly found encrusting the stones used by 
crab-catchcrs in mooring their crab-pots, in patches vary- 
'°g from one quarter to one inch in diameter. The cells are 
° v al, and horizontal, and their surfaces granular or frosted ; 
0,1 the lateral and upper portion is a short stout spine 
f ®tnoved from the aperture about one fourth ot the length 
?! the cell. The spine is short, but has a spreading base, and 
!. s sometimes placed laterally and at others immediately in 
'font. The apertures are round, unarmed, and terminal. It 
* e quently happens that small circular orifices are scattered 
° v er the polypidom, in the inter-cellular spaces, as if a few 
bad been abortive. 
PUSTULATA. Encrusting, calcareous ; cells ovoid, 
a lternate, in radiating lines; apertures semi-circular, with 
a Prominent rim. PI. xxii., fig. 2. 
flab. On stones and shells. Polperro. Goran, Mr. Peach. 
/• f bis species occurs in encrusting patches of about three 
° Q rtlis of an inch in diameter. It is calcareous, adnate, with 
cells alternately arranged in radiating lines. I he 
P e rture is semi-circular and prominent, or formed 
tu bula 
prominent, or formed by a 
— r rim. ThVp rosimal li P is either strai 6 1 "’ or sIi gbtly 
li t, ^ ilUo lhe cavity ot lhe mouth, and near it is a conoidal 
H Crc le, wliich lies immediately in front ; and this is among 
t e ear hest portions that become solidified. Willi the 
* Ce ption of this tubercle, the surface, in old specimens, is 
arl J smooth ; but in young ones it is minutely granular. 
