_ '1.1 ~ - 



of foe shell anterior bo che i)u>.iL.';xlor cariii. - --•.---- 



thirteen or fourteen high, flat-topped radial ribs, .separated bj' 

 sqiisrely impressed, deep interp-oaces of virtnall:' ■'■he same width; 



ai'eLL ijtihind the carina beariu^ nine radiMla oT >ji.-/ "' ?ter, 



the interspaces being usuallj' narrower than the ribs; ' . the 

 inters-oaces relativpi;^ eoarse, ooncentirio threads ^resent, arch- 

 ed (with the coiiucive aldu toward the umbo) in the " ""l- 

 atelj" anterior to the carina and also in the posterior area where 

 thej" mav cross the ribs; some or all of the ribs nodn.late'', the 

 nodules beiii^- globular in L'he luubonal t'.n'l 'Jas e::tre:!ie Li^-uerior and 



^■)OSterior regi f the shell, and transversely swollen elsewhere; 



tiv? first nine or ten ribs 'ororrossivelj? wider and. the first five 

 or six intersoacca wider triari elsewhere; the remaining ribs up 

 to the posterior carina usually squarely Iceeled, -vYith the con- 

 centric threa'''s of the interspaces present on the lo" rt of 



bhe rib, but not on the keel; immediately behind the carina both 

 ribs ajid interspaces narrower than elsewhere, bi^t increasing 

 slightly in width t or/ ard the posterior end; internal margins of 

 the valve ' ''' "hort, broad erenulations. 



Dimension g .- lat., 18.5 ram.; alt., 213 mm.; semidiam.., 9 mm. 

 ^emarhs ,- This S'oecies is r en-p r''-rabls "oroli ""i c ; it not onl" 

 far oiitnwnbers the other cockles, but it is the most abu.idant pelec; 

 pod in the f auj:a . Despite this unusually large re-oresentation the 

 characters are for the nrt^.t -op -rt r-'.iite constai't. :^st marked 



variation affects the sharpnG;Ss oi' the carina. In general, the 



