- 3?3 - 



concent rio lines occasionally appearing in the inter; on 



an-" portion of the shell; posterio- 'in of the valve deeply" 



serrate. 



Dir'.ensions .- lat., J57 niin. ; alt., 48 mm.; semiri.i ., 19.5 

 mn. 



I\e!nar>s .- A nuniher of valves of this interestir- " — "i-en 

 representative of the £. isocari'^ia Tinnaeus group is present. 

 The sculpturing is very elah'^rste and on portions of the shell 



st: "7 suggests, as Dall \.uis aptly remarked, twisted ribhons of 



candy. 7/hen the highly ornamented ^rill is eroded the rihs are 

 flat or suhrounded and smooth, except for a narrow r.e^ian stlLcus. 

 Yor:-g individiials are less elongated and more orhic-.L . '•'an 

 adults. 



j3, 1 in t^'iial eon is hbt he recorni^ed hy its sli"-htly elongated 

 form and iioclulated, tv/ifste i frill ihat uvci-to_^ti ' ' '^oj: 



side of the strong radial rihs. Brovrn and Pilshry ha icrihe:" 



a Gatiiia form, 0_, ctiriatTrm (l), which is so close ' ould 



(l). Proc. Acad. Tat. Sci., Philadel-oVjia, vol. 6", ' . :-Sb7, 



^1. 2T, fig. 11, 1911 (=2. spec , (vielloicht e Art) 



Toula, Jahi-h. i:.-k. geol. Reichsanstalt , vol. , . 721-722, 

 pi. 27, fig. 5, pi. ?S, fi^s. l-^a, h, 1 . 



he better, rjerhaps, to consider it a var ' ' if liu;-n.aleonis. 



The only constant " :es are the smaller size '"he sli^^ht- 



