- 1 



OAaDIUlvI {TRICOi:iOOAI©IA) TiiAm'TASTLliL n« 



2":) . 



-Deserioti on .- Shell small, o'blique, deeicle ^.1;- inflated; ant- 

 erior niargin roi^nding broadl;; into the gentlj" slopir.o- "base, o"b- 

 liqnely triznGated posteriorly; itmbones high, strong " , osog'jrate; 

 carina very strong, curved; portion of the shell : ' -r to the 



crrina sculptured with ten, relatively v/idc rihs, increasing in 

 sise from the anterior ;,:ai--in to the center of the shell ar.'d then 

 slightly decreasing, the oarinal rih heing stihroimded, the others 

 flat; the interspaces ai^teriorly narr9"."er than the rihs, to^rard 

 the carina oeconing hroader and much deeper; po-:, cu ' icr area much 

 depressed, omar.ented with seven narrow, low, flat rihs, wider 

 toward the margin of the shell; some or all of the ri> a^^.onted 



v.lth small, globular norlules, becoming slight 1;^ •. rii.....veioel^ elong- 

 atoi in the median ventral region; interspaces vvith fine concen- 

 tric stria'^i'^n'?; imTne'" lately before the umbo narrow, smooth pre- 

 sent ai.id oci-ii^ci che .„oo a siiuilar area ijcarce"' " ' ff erentiated 

 from the lo'.v first posterior lib. 



Dimensions .- L::t., 7.0 r.im. ; alt., 10 ::^m. ; idiam.. , 4 mm. 



3er:iarkh; .- ' le right valve of this bea.ioil'ull;, sculp- 



tured spe is at hand, ^t is distingrdshed by its small size, 



oblirne s'-a-oe, stroi-r:' c';irvGrl carina and the deep intervals betvveen 

 the ribs which i..ime ' iately preeeede the ■■ . is species can 



not be confused with ha 1 tense or its variety saymacense because of 



