286 LIMIDA. 
smooth, and ornamented posteriorly, as also the free portion of 
the right valve, by concentric plications or radiating ribs. 
Hinge-area triangular, transverse, striated in the same direction, 
edentulous, sometimes produced in the middle line; ligamental 
furrow median, longitudinal, straight, rather narrow. Muscular 
sear near the posterior margin; pallial line wanting. Externally 
the shells of this genus resemble those of Hinnites and Ostrea. 
Famity LIMID #&. 
Shell eared, white, gaping at the sides; hinge edentulous, with 
a central, triangular cartilage-pit. 
The large development of the internal thin layer of the mantle, 
forming an open bag, appears to be destined for hatching the 
eggs, and is no doubt also an important organ for retaining 
water while swimming. 
Mostly extinct, from paleozoic. Nearly 300 fossil species, 
but few of them in the new world. 
Lima, Bruguiére, 1792. 
Htym.—Lima, a file. Syn.—Radula, Klein. 
Distr.—20 sp., Norway, Britain, W. Indies, Canaries, India, 
Australia; 1-150 fms. The largest living species (L. excavata, 
Chemn.) is found on the coast of Norway. Fossil, 300 sp. Carb., 
Trias—-; United States, Europe, India. L. squamosa, Lam. 
(exxxil: 917.92); 
Shell equivalve, compressed, obliquely oval; anterior side 
straight, gaping, posterior rounded, usually close; umbones 
apart, eared ; valves white, smooth, punctate-striate, or radiately 
ribbed and imbricated; there is usually a thin, brownish 
epidermis; hinge-area triangular, cartilage-pit central; adductor 
impression lateral, large, double; pedal scars two, small. 
Animal: mantle-margins separate, inner pendent, fringed with 
long tentacular filaments, ocelli inconspicuous ; foot finger-like, 
grooved; lips with tentacular filaments, palpi small, striated 
inside ; gills equal on each side, distinct. 
The shell is always white; its outer layer consists of coarsely 
plicated membranous lamellz ; the inner layer is perforated by 
minute tubuli, forming a complete network.—CARPENTER. 
“The Lima moves or rather darts through the water like a 
scallop, but in a contrary posture. The hinder instead of the 
ventral end is in front, so that the mode of its progression may 
be compared to that of a fish swimming tail foremost. Some 
species construct dwelling-places called ‘nests’ out of frag- 
ments of shell, nullipores, gravel and other material, which they 
ingeniously fasten together by their byssal threads and attach 
to the roots of large sea-weeds. Several young ones often occupy 
