CONCHOLOGY. 73 



ShelL Subtriangular, inequilateral, inequivalve, with rounded 

 summits, feebly 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. 

 Animal. Body moderately compressed ; a byssiferous abdo- 

 minal appendage ; edges of the mantle furnished with tentacular 

 cirrhi in several rows ; mouth surrounded with a very thick 

 fringed lip. 



Shell. Oval, more or less oblique, nearly equivalve, subauricu- 

 lated, regularly gaping at the interior portion of the inferior edge ; 

 summits anterior and distant ; hinge buccal, longitudinal, tooth- 

 less ; ligament rounded, nearly exterior, inserted in an excavation 

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

 very distinct parts. Inhabits the Indian, Australasian, American, 

 and Mediterranean sea^. Six living species. Eleven fossil. 



Lima inflata. Lima glacialis. 



L. squamosa. L. fragilis. 



L. annulata. L. linguatula. 



2. (jenus Pecten. 



Animal. 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, soUd, equivalve, equilateral, auricu- 

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

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

 almost altogeth^ internal, and filling a triangular excavation 

 under the summit; a single subcentrul muscular impression. 

 8 



