MARINE MOLLUSCA OF THE UNITED STATES. 197 



5. P. ornatus, Lamarck. Fig. 541. 



Anim. sans Vert., vi. 176. 1819. 



Subequivalve, depressed, inequilateral, oblique, ribs thirty to 



thirty-six, alternately smaller and subscabrous; one ear minute, 



yellow ochraceous or white profusely blotched with angular red 



markings. 



Length 1 inch, width 20 mill. 



North Carolina, southicards. 



6. P. nodosus, Linnaeus. Fig. 542. 



(Ostrea.) Syst. Nat., edit. xii. 1145. 1767. 



Shell with nine thick rounded ribs, and strong radiating stria? ; 



ribs with large hollow vesicles. Reddish-brown, orange, or white. 



Diameter 2-5 inches. 



North Carolina, southwards. 



P. pustulosus, Verrill, Araer. Journ. Set, v. 14. 1873. " St. 



George's Banks." 



This is probably, from its small size, an immature shell. It has 

 not been figured, and besides, is extra-limital. 



Genus LIMA, Bruguiere. 

 Encyc. Meth., t. 20, f. 6. 1792. 



The animal has double mantle-margins, the 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 Limas are either free or spin a byssus ; some make an 

 artificial burrow when adult, by spinning together sand or coral 

 fragments and shells. The valves are always white. About 

 twenty species are known. 



1. L. scabra, Dillwyn. Fig. 543. 



Recent Shells, 271. 1815. 



Ostrea glacialis, Gmelin (pars), Syst. Nat. 



Shell oval, subequilateral, with numerous subscabrous stria? ; 



margin entire. 



Length 2.25, width 1.5 inches. 



Southern Coast. West Indies. 



2. L. squamosa, Lamarck. Fig. 544. 



Anam. sans Vert., vi. sp. 2. 1819. 

 Shell ovate, inequilateral, with strong, scaly ribs; hinge oblique; 

 margin plicated. 



Length 1.5, width 1 inch. 



SoutJiem Coast to West Indies. 



