- 98 



AHOA (AOAR) PROPSRTUA n. sp. 



Deseri oti on.- Shell small, heavj', moderately elongated^ well 

 inflated; rounded anteriorly, the eirrve decidedly convex; poster- 

 ior end produced below, subroimded above; base gently arcuate, dcs 

 cending tov/ard the posterior end; izmbone s tumid, hi?li and broad; 

 posterior ridge prominent, rounde^>; ventral half of the shell with 

 a slight median depression; external surface sculptured with num- 

 erous fine radial ribs separated by narrow interspaces except on 



the posterior slope where the ribs a:.'e wider and the interspaces 



• 

 of about the same width; the ribs occasionally dichotomous : con- 

 centric sculpture developed throughout by nodulations on the ribs; 

 cardinal area. narrow, excavated, widening slightly in front of the 

 umbo, transversely striated; hinge with a continuous series of 

 teeth, the Iteeth oblique at the extremities, small and vertical m 

 me'Ually; inner niar~in of the volve without definite crenulations. 



Di'-ensions .- I.'ax. length, ii mm.; max. alt. 5.8 r;im. ; semidiam. 

 1,8 mm. ; length of hinge, 4,5 mm. 



This species is described from a single valve. It Is immed- 

 iately distinguished from A. reticulata by its less elongate form, 

 more rounded posterior ridge and decidedly finer scijlpture. The 

 Oaloosahatchie A. millifila Dall(l) is larger, proportionately 



(1). Trans, "vag-ner Free Inst. Sci., Philadelphia, vol. ?, ot. 

 6. p/ 1629, pi. 5 6, figs. 21, 24, 1902. 



