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AROA (SOAPHARGA) AGHASTIIA n. sp. 



DesGription .- Shell an all, thin, moderately inflated, high- 

 er posteriorly, oompressed in the posterior dorsal region; poster- 

 ior nmrgin triuicate:!; ventral margin curving gently in the poster- 

 ior half and more rapidly in the anterior half, anterior mar!?in 

 carving abruptly upward; both lateral marrin Joining the dorsal mar- 

 '^'in by sharp arigles, the posterior angle being slightly more than 

 90°; umbones low, relatively brosd, placed at ahont the anterior 

 third of the length, with a very slight nsdian sulcus; e-rternal 

 surface sculptured with forty lov;, narrow, flat radial ribs, broad- 

 er and flatter on the posterior slope, separated by narrower inter- 

 spaces; in the interspaces faint concentric lines, ^'^ersistent across 

 the ribs, except those on the posterior slope, producing slight 

 nodulations; cardinal area of me-iura width, with faint longitudinal 

 strlations; . ;.-.je long, straight, '-.ith ntunerous fine teeth; inner 

 margin v;ith numerous, short crenulations. 



Dimensions .- Length, 21.8 mm.; alt., 12.8 ram.; semidiam., 

 5 ram.; length of hincre, IG mm. 



Reracrks.- The compressed posterior dorssl region produces an 

 auricula te effect which is more pronouncer! on yomig individuals. 

 The ventral mar-in ascends rapidly toward the anterior end. These 

 features, together with the numerous narrow, flattened radial ribs 

 and small size of the shell, are distinguishing characteristics. 



