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POPULAR CONCHOLOGY. 



shaped, inequivalve, and slightly eared; a groove or pit 

 in each valve, which increases in size with age, and bears 

 the ligament ; bosses unequal and distant, the lower valve 

 rather convex, with the sides 

 reflected over, upper valve 

 flattish ; a large yellow byssus 

 passes through a sinus in the 

 shell. Animal greatly resem- 

 bling the Pecten; the mantle 

 cloven in its whole length, the 

 edge thickened, furnished with 

 several rows of cirrhi, and 

 having eyes ; two pair of large 

 leaf-shaped gills on each side ; 

 the foot is vermiform, and has 

 at its base a thick glossy silken 

 byssus ; the mouth is pretty 

 large, oval, having on each side 

 a pair of striped triangular 

 tentacula. — 1 species. 



The only species known (P. spondyloideum) is found in 

 the Indian Seas, at great depths, and is rare; it is white, 

 slightly tinged with purple near the bosses ; and buries 

 itself partially in madrepores, in crevices of its own 

 boring. 



Lima. Brug. — Shell longitudinal, nearly equivalve, 

 obliquely fan-shaped, slightly eared; surface smooth, or 

 striated ; valves gaping near the bosses, which are distant, 

 separated by an area ; hinge without teeth but having a 

 triangular pit for the ligament ; byssus passing through a 

 wide sinus. Animal, oval ; mantle freely open, its margins 

 pendent and fringed with long tentacular filaments : ocelli 

 absent or inconspicuous ; no siphons ; body produced, in part 



