- ir-1 - 



pexata Say (-A. oampechensis Dillwyn). The Bowden specim.ns are 

 however, muoh smaller than the typical tolepla . proportionately 

 less inflated, slightly more romided posteriorly and have sulcated 

 iimbones, a few more ribs and narrov/er interspaces. In view of these 

 differences it seems advisable at the present tirnc to consider 

 the Bowden form a depauperate variety. 



The yormg of A. oampe c hens is Dill^vynfl) of the same size have 



fl). Descr. Oat. Rec. Shells, vol. 1, p. 208, 1817. 



a longer postero-dorsal margin which meets the late ml margin at 

 a sharper angle, a straighter base, shar-ner and more conspicuous- 

 ly nodulated sculpture and unsulcated umbones. A. brightonensis 

 Maury (2) and A. billingsiana llaury (Z), both from an Upper Oligo- 



(2). JouJT. Acad. Hat. Sci., Philadel"ohia, 2nd ser., vol. 15, 

 pp. 46-47, pi. 8, figs. 4-6, 1912. 



(S). Idem. pp. 45-46, pi. 8, figs. 2, 5. 



cene horizon at Brighton, Trinidad, are more elongate, less in- 

 flate"! and differ also in sculpture. 



Occurrence .- lower Miocene : Bowden be'^s, Bowden, Jamaica 

 (Dall, 1-98)/ 



