

posteriorly, the rostrum being slightly recurved; ventral margin 

 gently arcuate; umhones lov;, tumid, proxi-ate, slie-htly opistho- 

 gyrate ; luniile not differentiated, represents"! hy a sliphtly de- 

 pressed narrow zone; escutcheon sharply differentiated, broad, 

 extending to the tip of the rostrum, bounded by a stron?, sharp 

 carina, which becomes slightly broader and flat dis tally, the 

 exterior eds-e being sharp throughout while the edge facing the 

 escutcheon is lower and less sharp; i::mediately anterior to the .- 

 rostral carina is a shallov/ sulcus v.hich is best defined in the 

 umbonal region and scarcely affects the ventral mare-in; anterior- 

 ly a shallow, but sharply li alter!, sulcus runs from the umbo to the 

 ventral margin, the outline of which it rarely affects; external 

 siirface sculptured with closely-set, regular, continuous concen- 

 tric rugae, equally strong throughout find persisting across the 

 rostral carina- and escutcheon; teeth strong, about fifteen behind 

 and sixteen before the deeply-set, small triangular chondrophore. 



Dimensions .- Length, 6.5 mm.; alt. 3,8 nun.; semidiam. 1.5 mm. 



Remarks .- Although the forms referrable to this species are 

 quite variable, they may usually be recognized by the pointed, 

 slightly recurved rostrum, the sharp posterior carina and the 

 broad, long escutcheon v/hich is conspicuously sculptured by the 

 persistent concentric rue-ae. Variations occur iorinci pally with 

 regard to shape and the size and spacing of the concentric rugae. 

 The tynical indigene is rather elongate:^-, but some forms tend to 



