113 



LEPRALIA. Johnston. 



Generic Character: Polypidoni calcareous, or memhranoT 

 calcareous, adnate, crustaceous, spreadinjij circularly, 

 formed of a layer of urceolate cells in jiixlaposition, and 

 arranged in a quincunx ; aperture terminal, often covered 

 with an operculum. Polypes ascidian. 



L. PEDILOSTOMA. Encrusting, calcareous ; cells ovoid, 

 alternate, frosted, with a stout spine on the upper surface ; 

 apertures terminal, round, unarmed. PI. xxii., fig. 14. 



Hab. On stones about one mile from the shore, common; 

 Polperro. Goran. 3Jr, Peach. Falmouth. 



This, with several of the following species, are here des- 

 cribed for the first time. They have long lain by me, but as 

 they could not be satisfactorily refered to any described 

 species, they were omitted in the Report of the Cornwall 

 Polytechnic Society, till their specific diflercnces could be 

 decided on. Having been supplied with a collection from 

 various localities by my friend Mr. Peach, and having com- 

 pared them with those in my own collection, they prove to 

 be distinct ; and the one now under consideration has bvvn 

 named pedilostoma by Mr. Hassal. 



It is very commonly found encrusting the stones used by 

 the crab-catchers in mooring their crab-pots, in patches vary- 

 ing from one quarter to one inch in diameter. Tlie cells are 

 oval, and horizontal, and their surfaces granular or frosted ; 

 on the lateral and upper portion is a sliorl stout spine 

 removed from the aperture about one fourth of thtt length 

 of the cell. The spine is short, but has a spreading base, and 

 is sometimes placed laterally and at others immediately in 

 front. The apertures are round, unarmed, and terminal. It 

 frequently happens that small circular orifices are scattered 

 over the polypidom, in the inter-cellular spaces, as if a few 

 cells had been abortive. 



L. PUSTULATA. Encrusting, calcareous ; cells ovoid, 

 alternate, in radiating lines; apertures semi-circular, with 

 a prominent rim. PI, xxii., fig. 2. 



Hab. On stories and shells. Polperro. Gorat), Mr. Peach. 



This species occurs in encrusting patches of about three 

 fourths of an inch in diameter. It is calcareous, adnate, vTitli 

 oval cells alternately arranged in radiating lines. The 

 aperture is semi-circular and proininent, or formed by a 

 tubular rim. The proximal lip is either straight, or slightly 

 arched into the cavity of the mouth, and near it is a conoidal 

 tubercle, which lies immediately in front; and this is among 

 the earliest portions that become solidified. Willi the 

 exception of this tubercle, the surface, in old specimens, is 

 nearly smooth ; but in young ones it is minutely granular. 



