262 OSTREADiE. 



LIMA, BrugiSre, 



Shell more or less obliquely oblong, equivalve, usually 

 inequilateral, closed in front, more or less gaping at the 

 sides, eared on each side of the hinge. Surface smooth, 

 or striated and grooved in a radiating fashion, the ribs 

 often scaly. Beaks separated by a rhomboidal area. Liga- 

 ment occupying the expansion of the hinge-line on each 

 side of a strong cartilage, set in a triangular pit under 

 the beak of each valve. Pallial impression entire, muscular 

 scar eccentric. 



Animal oval, mantle freely open, its margins pendant 

 and fringed with long tentacular filaments. Ocelli absent 

 or inconspicuous. No siphons. Body produced, in part 

 linguiform. Foot small, ligulate, furnished with a byssal 

 groove. Labial palps subtriangular, small, pectinated ; 

 mouth surrounded by tentacular filaments ; anal tube 

 cylindric, externally visible. Branchial leaflets equal on 

 each side. 



The species of this genus bear a close afiinity to Pecten^ 

 yet constitute a very natural group of themselves. The 

 Lima; appeared in very ancient epochs, and during the 

 oolitic period, species were comjmratively abundant and 

 attained great dimensions. The fossil genus Plagiostoma 

 is synonymous with Lima. Some twenty well marked 

 forms inhabit existing seas, living in various depths of 

 water, either free or moored by a byssus or enveloped 

 in nests formed of byssal filaments. 



The animals are very beautiful and curious, and often 

 much larger than their shells, which in the gTeater number 

 of species, though remarkable for elegance of outline and 

 sculpture, rarely present any other colour than a milky 



