PELECYPODA. [Eulamellibranchia. 



lateral laminae distant from the cardinals, anterior and posterior in 

 the right, with corresponding sockets in the left valve ; cardinal teeth 

 radial, 2 in each valve, the posterior tooth larger and often bifid, but 

 any or all of the teeth may be obsolete or absent. 

 Silurian to Recent. 



KEY TO GENERA. 



A. Ligament very small, an internal resilium ; right valve with 



1 cardinal tooth . . . . . . . . LOEIPES. 



B. Ligament and resilium not internal ; right valve with 2 cardinal 



teeth . . . . . . . . DIVAB.ICELLA. 



C. External ligament obsolete, a strong internal resilium ; right 



valve with 1 narrow lamina having a minute cardinal hook 



at the proximal end . . . . . . . . MONTACUTA. 



Genus 1. LORIPES, Cuvier, 1817. 



Loripes, Cuvier, Regne Anim., ii, 1817, 482. Type: Tellina lactea, Gmel., 

 not of Linne == Loripes lucinalis, Lamarck. Not Loripes, Schweigger, 

 1820. Thyatira, Gray, 1847 : not of Hubner, 1816. Ligula, Menke, 

 1830 ; not of Montagu, 1803. Liicinida, d'Orbigny, 1846. Lucinideu, 

 Barrois, 1887. 



Animal with an elongated anal siphon, the branchial orifice not 

 produced ; foot extremely long, vermiform. 



Shell tumid or compressed, suborbicular, with feeble sculpture ; 

 lunule narrow, elongate, an obscure anterior dorsal area indicated. 

 but no posterior area or escutcheon ; ligament almost or wholly 

 internal, obsolete ; the resilium deeply immersed ; hinge with the 

 posterior laterals and right anterior cardinal usually absent ; margins 

 entire, anterior adductor-scar long and narrow. 



Distribution. In most seas, but chiefly found in the Mediterranean, 

 the West Indies, and Philippines. 



1. Loripes concinna, Button, 1885. Plate 63, fig. 8. 



Loripes concinna, Hutton, T.N.Z.I., xvii, 1884 (1885), 323 ; op. cit xviii 

 363 ; Plioc. M., 83, pi. 9, f. 90 ; Medley, T.N.Z.I.. xxxviii, 74. 



Shell small, suborbicular, the beaks turned forward, concentrically 

 finely ribbed, slightly inequilateral. Beaks slightly raised, convex, 

 incurved. Anterior end a little longer, semicircular, the dorsal margin 

 narrowly concave in front of the umbones ; posterior end truncated 

 at the middle, dorsal margin sloping, lightly convex, basal margin 

 broadly rounded. Lunule lanceolate, the left half narrower. 

 Sculpture consisting of regular, fine, and sharp concentric riblets, 

 the interspaces of about the same width. Colour light brown to 

 whitish. Interior white, porcellanous, the area inside the pallial line 

 radially striate. Margins finely crenate. Hinge : Right valve with 

 a large triangular and oblique cardinal, occasionally bifid, and an 

 anterior and posterior feeble lateral tooth ; left valve with 2 diverging 

 cardinal teeth, a triangular socket between them, lateral teeth obsolete. 

 Ligament partly external, with a shorter resilium. Adductor-scars : 



