- ll-V 



ARGA (SOAPIIAHGA) THOMASEIISIS n. sp. 



Description ,- Shell, s;nall, well inflated, moderately inequi- 

 lateral, slightly produced posteriorlj-; anterior end of the dorsal 



mars-in rou: ded; ventral margin almost symmetrically arcuate; 

 rourided anteriorly and posteriorly; umhones moderately high, plac- 

 ed anterior to the me'^ian horizontal, the tip very sli.^htly impress- 

 ed medially; e" ternal surface sculptured v;ith thirty-six narrow, 

 square-topped, clocely set radial rihs separate! by narrower inter- 

 spaces; the anterior seven or eight ribs and the accompanying in- 

 ters-oaces relatively wide; the nezt eight narrow and the succeed- 

 ing ones -oroprressively sllp-htly broader, those on the posterior 

 slope broadest and flatest; concentric sci.ilpture of irregular, in- 

 cons-oicuoua lines v/hich faintly and unevenly nodulate the anter- 

 ior and median ribs; cardinal area moderately v/ide, with a single 

 ligament groove behind the umbo; teeth numerous, vertical, except 

 at the posterior end of the series; ini'ier m.argin of the shell or- 

 nam.ented with numerous, deep, long crenulations ; interior of the 

 shell mar'rer' with fine, inconspicuous radiating lines. 



"Dir.ensioiTS .- Length, 19.5 mm.; alt., 12 mm.; semidiam., 5.1 

 mm.; length of hinge, 14 ram. 



Hem.arks .- Phis species is re-':)resent ei^ by a left valve. It 

 may seem unfortunate to add another species to the alreat^y long 

 list of Bowden Scapharcas, especially the species rests on a single 



