L 
CONCHIFERA 413 
straight, gaping, posterior rounded, usually close; umbones 
apart, eared; valves smooth, punctate-striate, or radiately 
ribbed and imbricated; hinge area triangular, cartilage pit 
central’; adductor impression lateral, large, double; pedal 
scars 2, 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 lamellze; the inner layer is perforated by 
minute tubuli, forming a complete network. (Carpenter.) 
The Limas are either free or spin a byssus; some make an 
artificial burrow when adult, by spinning together sand or coral- 
fragments and shells, but the habit is not constant. (Forbes.) 
The burrows of LZ. hians are several times longer than the shell, 
and closed at each end. (Charlesworth.) ‘‘ This species is 
pale or deep crimson, with an orange mantle; when taken out 
of its nest it is one of the most beautiful marine animals to look 
upon, it swims with great vigour, like the scallop, by opening 
and closing its valves, so that it is impelled onwards or upwards 
in a succession of jumps. The filaments of the fringe are 
easily broken off, and seem to live many hours after they are 
detached, twisting themselves like worms.” (Landsborough.) 
L. spinosa has conspicuous ocelli, and short filaments. 
Sub-genera, Limatula,S. Wood. L. sub-auriculata, Pl. XVI., 
Fig. 13. Valves equilateral; 8 species. Greenland—Britain. 
Fossil, Miocene—. Europe. 
Limea, Bronn. L. strigilata, Pl. XVI. Fig. 14.* Hinge 
minutely toothed. 
Fossil, 4 species. Lias—Pliocene. The recent Limea? 
Sarsti (Lovén), Norway (=L. crassa of the Aigean ?) has the 
mantle-border plain. Some of the larger recent species have 
obscure lateral teeth. 
Distribution, 20 species. Norway, Britain, West Indies, 
Canaries, India, Australia; 1—150 fathoms. The largest living 
species (L. excavata, Chemn.) is found on the coast of Norway. 
Fossil, 200 species. Carb.? Trias—. United States, Europe, 
India. The so-called Plagiostoma spinosuwm is a Spondylus. 
SPONDYLUS (Pliny) L. Thorny-oyster. 
Type, 8. geedaropus, L. 
Example, 8. princeps, Pl. XVI., Fig. 15 
* After Bronn; the figure in Brocchi does not show the teeth. 
