.A?? - 



posteriori;.;; oiitl-'. obli' ovate-tr' 1 to 



almoc ^l'->'-i - '-n-^'-^- -, n vr. ''-terior we' t'-t '^ 



o>)lif(_uel;,' oubtruiic :tl„; rouiicled; ;trioall: 



arcuate; umbones tiinid, moderately h'. riiia dis- 



trail;/; anoerior and posterior ends of the shell ■ ' ' i radial 



markings, the posterior area oeinr- 'r/idcr than t .erior; the 



reinai"- ' -"'' ■'*■'' '^'^■' '-• ~""cll "^ooi-n -,-,?>• nunierons, :, dl. , . Iil'^ 



radial markings; entire surxac-e of the shell wi'^ centric 



markings, in the iimhonal re^'ion more re^-nlar" -oars- 



er; thi^ hiix'-i. ' ■'■ - ^'--^ -.-,'.--■'■■ ^ - - - ■ - Li_.l 



radia^ls minutely' erenulated; .yen';ral half ox th^ rrel s^^r^aoe 

 with rrr.. faint radii. 



I)imen5i ons .- Lat., .; " ., •; ■ t ^'^' -"'• 



Remarks.- "/it Ir.vo of the present Bowder: of this 



long-ranging species are large end t;'"oir'o"' ' ' , the 



valves hsv''.-' •. outline that i-ui-tis ' t-l^ elongate to 

 almost sulDCircular. The e'-^ternal radii could .soarcel^" "be tey 



rihs since the;;,' harri] '-ct the co-to-nr es of 



the sl^ell. The s\u __ . , , -M^ y both ^h 

 radial and concentric markings stanri ' ' 'c-lief, prodiicin," 

 a cancellated effect. 



0_. con'rprgssu.m Dall (i), 'ip'ic- . ' ■•,--. ^ -"- ^ 



