PEOTO, 253 



. Jndistinct lateral teeth ; ligament large, supported on prominent 

 fulcra ; muscular impressions two in each valve, sub-orbicular, 

 . , — 06s. The name given to this shell refers to its place of abode, 

 being found in rivers. It is the Venus sub-viridis of some 

 authors, although being a fresh-water shell, and having an 

 incrassated hinge, and a smooth, thick epidermis, it is most 

 distinct from that genus. It is described bj Bowdich under the 

 name Megadesma, on account of its large ligament, and by 

 Lamarck under that of G-alathgea, a name previously used by him 

 ^ for a genus of Crustacea, P. radiata, fig. 115. Megadesma 

 , appears to be the preferable name, since it has the right of pri- 

 ority over Potamophila. It is found in Africa. PL v. fig. 115. 

 PEIAMUS. Beck, 1837. Halia, Kisso, 1826. A genus com- 

 posed of AcHATiNA Priamus, Lam. Btjccintjm Stercus-Pulicum, 

 Chemn. Conch. .9. t. 120. f. 1026-7. This shell is ascertained 

 to belong to. a marine mollusc, having a horny operculum, and 

 therefore is justly considered to form a distinct genus, allied to 

 the Buccina and Struthiolarias. PI. xxv. fig. 545. 

 PEISODON". Schum. Hteia, &c. Auct. Pig. 144. 

 PEODTJCED. (Productus, prominent.) A term applied to the 



spire of univalve shells, or to any other prominent portion. 

 PEODUCTA. Sow. (Productus, produced.) Fam. Brachiopoda, 

 Lam. — Descr. Equilateral, inequivalve, thick, striated ; one valve 

 ' .. generally convex, with the margin inflected, produced ; the 

 other valve flat, or slightly convex, with the margin reflected ; 

 hinge rectilinear, transverse. — Ohs. The peculiarity of this 

 genus, from which it derives its name, is the manner in which 

 the anterior margins of the valves are drawn out and overwrap 

 each other. The genus is only known in a fossil state. Species 

 occur in Mountain Limestone, and Transition Limestone of 

 older date. P. depressa. PI. xi. fig. 266*. 

 PEOSEEPINA. Gray ? Pig. 274, represents a small shell be- 

 longing to the Hehx tribe, to which it is belieyed, Mr. Grray 

 has applied the name Proserpina nitida. We do not know how 

 the genus is defined. PI. xiii. fig. 274. 

 PEOTO. Defr. A fossil shell resembling Tijeitella, but 



