although the "Olifroeene of Jamaica" is the only horizon and 

 local ity friven. Later in the V/agner Institute papers the three 

 forms are differentiate t. Jhe Santo ■i-'oninfian form under the 

 name disparilis a-^parently cannot "be distinguished from the 

 Bowden soecies. ^rabo 's Gosta Rican Miocene specimens of dis~ 

 parills (l) are poor b'lt closely resemble heterorrena . JTone of 



(1). loc. Git., p. 345, 1081. 



the Oosta Rican Pliocene disparili s (S) are as large, hut valves 

 of the same size shov*' no constant differences. In both those 



(2). loc. eit., p. .'^71, 1881. 



cases only right valves are available.- for com'oarison. ■:'he 

 recent disparilis is lar.eer, v/ith ir/ider and h'p-her umbones and 

 less regula, r sculr)-':ure . 



Occurrence .- Up-oer Oligocene: Ohipola marl, "Florida 

 (l^all, 1898); Oak '"-rove sand, Florida (Dall, 1808); Gatun 

 formation, Panama (Dall, V.l 3); ^nto Jomingo (^Jabb, 187S; I'uppy, 

 187d, 1875); louver F.io eene : Bowden beds, Bowden, Jamaica 



(Gup-.^y, 1866, 187^.; Ouv.y and .Oall , 1895; TJall , 10Q8). i'ioGone: 

 Ohoe"'-:?hatchie ijr.;iation, ':'lorida (Dall, 1808); ? 3apote, Jos a 

 Rica (Gabb, 1881). Pliocene: Jaloosahatchie marl, Florida 



