78 CONCHOLOGY. 



Shell. Subtriangular, inequilateral, inequivalve, with rounded 

 summits, freely marked, unequal and distant : the right valve 

 inflated, widened at its inferior and posterior edge, sloped ante- 

 riorly, and subauriculated, the left not being so ; hinge toothless, 

 anterior or buccal ; ligament inserted in an oblique cavity pro- 

 longed outwardly to the summits, and carried within into a spoon- 

 like cavity. Inhabits the Indian Ocean. One species. 

 Pedum spondyloideum. 



2. Genus Lima. PI. IX. 



.Animal. Body moderately compressed ; a byssiferous abdo- 

 minal appendage ; edges of the mantle furnished with tentacular 

 cirri in several rows ; mouth surrounded with a very thick fringed 

 lip. 



Shell. Oval, more or less oblique, nearly cquivalve, subauri- 

 culated, regularly gaping at the anterior portion of the inferior 

 edge; summits anterior and distant; hinge buccal, longitudinal, 

 toothless ; ligament rounded, nearly exterior, inserted in an exca- 

 vation in each valve ; a central muscular impression, divided into 

 three very distinct parts. Inhabits the Indian, Australasian, 

 American, and Mediterranean seas. Six living species. Eleven 

 fossil. 



Lima inflata. Lima glacialis. 



L. squamosa. L. fragilis. 



L. annulata. L. linguatula. 



3. Genus Peden. PI. IX. 



minimal. Body more or less compressed, orbicular ; mantle 

 furnished with a single row of tentacular papillae, and with small 

 oculiform, pedunculated disks, with regular spaces between them; 

 rudiment of a canaliculated foot, and a byssus ; mouth surrounded 

 with fleshy appendages, irregularly ramified. 



Shell. Free, regular, thin, solid, equivalve, equilateral, auricu- 

 lated ; summits contiguous ; hinge toothless, a ligamentous mem- 

 brane throughout all its extent, besides a short, thick, ligament, 

 almost altogether internal, and filling a triangular excavation 

 under the summit; a single subcentral muscular impression. 



