994 



PELECYPODA. 



[Eulamellibra nchia. 



generally smooth ; pallial sinus free, narrow ; hinge with. 3 cardinals 

 in each valve, the anterior right and posterior left cardinals entire, 

 the others often bifid. 



Distribution. European seas, Senegal, Brazil, Indian Ocean, China, 

 Australasia, &c. 



Fossil. Cretaceous and Tertiary. 



Vernacular Name. Carpet-shell. 



KEY TO SUBGENERA. 



A. Sculpture not divided into areas, reticulate ; internal margins 



smooth ; pallial sinus rounded in front ; all cardinals more 



or less bifid . . . . . . . . . . RUDITAPES. 



B. Sculpture divided into 3 areas, the middle being chiefly radial ; 



internal margins sharply crenulated ; pallial sinus pointed 



in front ; the middle cardinals usually bifid or grooved . . PROTOTHACA. 



Subgen. 1. RUDITAPES, Chiamenti, 1900. 



Rnditapes, Chiamenti, Re vista Ital. Sci. Nat., xx, 1900, 13. Type : Venus 

 decussata, L. Amygdala, Ro'mer, 1804 ; not of van Phelsum, 1774, nor 

 Amygdalum, Megerle, 1811. Cuneus, H. and A. Adams, 1857 ; not of 

 Da Costa. 



Animal with the siphons wholly free from each other ; the foot 

 byssiferous. 



Valves convex, oblong ; surface dull and feebly coloured ; 

 sculpture strong distally, more or less reticulate, the concentric- 

 ridges more or less inosculating anteriorly and feeble on the middle 

 of the shell, the radial sculpture stronger ; internal margins smooth ; 

 the pallial sinus horizontal, large, free below, rounded in front ; 

 the lunule circumscribed, the escutcheon feebly defined ; all the 

 inner cardinals more or less bifid. (Dall.) 



KEY TO SPECIES. 



A. Shell small, thin and fragile, radial lines inconspicuous, uniformly 



white, median cardinals grooved, interior white . . . . fabagellit. 



B. Shell moderately large, solid, radial lines distinct, yellowish- white, 



young shells with radial zigzag markings, the 2 posterior right 

 and the left median cardinals grooved, inside often violet 

 posteriorly . . . . . . . . . . . . intermedia. 



1. Paphia fabagella, Deshayes. 18">4. Plate 55, figs. 1, a, 1>. 



Tapes falxKjvlla, Desh., P.Z.S., 1853 (1854), 10 ; Conch. Icon., xiv, pi. 13, 

 f. 60 ; Romer, Moiiogr. Gen. Venus, 91, pi. 31, f. 2 ; C.M.M., 72 ; Crit. 

 List, 46 ; M.N.Z.M., 151 ; Chall. Rep., xiii, 116 ; Hedley, Rec. A.M., v, 

 89 ; Suter, T.N.Z.I., xxxviii, 318. T. reticulate, T.-Woods, P.R.S. Tas., 

 1876, 159. 



Shell oblong-ovate, thin and fragile, tumid, very inequilateral, 

 rather compressed, finely reticulated, white. Beaks at about the 

 anterior fifth of length, very little raised, acute, directed forwards. 

 Anterior end shorter, very narrowly rounded, the dorsal margin 



