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 witk tentacular 
cirri in several rows ; mouth surrounded with a very thick fringed 
lip. 
Shell. Oval, more or less oblique, nearly equivalve, subaurt- 
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 inte 
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 Pecten. PI. LX. 
Animal. Body more or less compressed, orbicular ; mantle 
furnished with a single row of tentacular papille, 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. 
