- ?06 - 



raargine interno crenulata." (Gmelin, 1792, p. .'^504), 



Shell of ■'■■"^ ■''■ ' nm size, irregularly; traxisverselr '"^'bovate; at- 

 tached hj- left valve; right valve moderately convex posteriorly-, 

 compressed toward the anterior niar^'in; umhones large for the 

 sise of the shell, prosogj^rate , foi-rning about one and a half whorls; 

 external sciilp-ture consisting of irregiolar, more or less over- 

 lapping concentric lamellae, crenu" . and pro'"^. at irregular 

 intervals, sculptured with fine obsolete radial striae. 



Dimensions .- Right valve; lat., 27 mm.; alt., 23 mm.; 

 di sri . , 8 mm . 



Remarks.- The collections at hand have furnished a single 

 right valve that h?.s the characteristic features of the recent 

 forms assignee" : ..pecies. Its occurrence in the Bowden 



be^s would be received with suspicion if the shell '^id not have 

 the characteristic appearance of other Bowden specimens. Because 

 of its much larger size, larger umbo, more foliaceous and "spinose" 

 Ismellee bearing fine radisl striae, this valve is sharply differ- 

 entiated from right valves of the ascociated involuta . 



As noted above, at least some of Gabb's Santo Domingian 

 Ohamas are similar to this Bowden forsi. 



Occurrence .- Uprier Oli^^o'^ene: . ..':o Do (Gabb, in72) 



Lower Kioeeiie : Bowden -jt ;j, ^owden, Jamaica. Pliocene: li- 



mon, Costa ?dca (Gabb, 1881). Pleistocene: The Antilles and 

 Oiiraoao (Dall, igc^). Recent; Tampa to Gur.-:c' / c :^ rta, /" 



'^:^azil in to r87 fathoms. 



