- 47 - 



KUOUIA (PLA3IA3AREPTA) HILII n. sp. 



Desoriptlon ,- Shell of raediuin size, thin, polished, decidedly 

 inflated, ineq^ii lateral; outline transversely- suheiliptioal, roimd- 

 e ". posteriorly, produced and rounded anteriorly, ventral niargin 

 gently arcuate; umhones low, opisthoeryrate ; external surface sculp- 

 tured with well-defined, numerous, regular concentric rugae, which 

 hecone cro7/ded and less prominent on the dorsal half of the shell, 

 the umbo being almost smooth; chondrophore relatively large, elong- 

 ated, suhtri angular, its axis oblique and c -rved , deep^-y set, plac- 

 ed immediately in front of the umbo; hinge-tteth short, in two 

 series, decide'^ly discrepant in length; the anterior series longer, 

 moderately curved, including fifteen or sixteen teeth progressively 

 reduced in size t ov/ard the chondrophore and continuing almost to 

 the tip of the umbo, the last few treth being placed along the 

 upper anterior margin of the chondrophore; posterior series short, 

 straight or slightly concave, numbering five or six teeth of 

 virtually the same size, the series ceasing abruptly at the chondro- 

 phore; inner margin of the valve smooth; internal surface of the 

 shell polished; muscle scars and pallial line obscure. 



Dir.: ens ions .- Length, 8.9 mm.; alt., 6.9 mm.; semidiar.., 1.9 mm, 

 Remarks .- The subelliptical o;rf;line, inconspicuous urabones, 

 well defined and regular concentric rugae of this species, which 

 is represented by a number of valves, prod ice a facies which is 



