- 255 - 



face sci.apture." (Dall, 1-308), 



I'ype looslity .- Bowden, Jamaica. 



Shel"! I'arp'e, thin, compressed, irregulcrlj' s Tib orbicular; 

 irregultrl- ivarped and folded, the brofid undi:' '' being most 



pronoimced at the ventral margin, hut not definitely plicater!; inn- 

 honal region occacionally sv/ollen; erterior surface pr^i:! iV-ured 

 r.-ith fine, ^' ontinuous, swollen radial striae, broken up into 

 longer or shorter portions or interrui^ted so frequentl"; that 

 thev produce a finely; ^up.tulose appearance; bysssl plug on right 

 valve elongated, triangular, almost extending to the cardinal 

 margin; internal cardinal "rugosities" verj? feeblj? developed or 

 obsolete; ri^-^ht v^^-'e v>'ith strong cardinal or^iv.'^, diverging at 

 an acute angle; left valve v.ath a sharply defined, large, tri- 

 angular umbonsl depression into which the crura of the right 

 valve are received, the anterior and posterior distal portions of 

 the depression separated by a triangular elevated area corres- 

 ponding to the depressed area betrvveen the crura on the right 

 va^ve. 



5emar 'cs . - Several more or less incomplete valves of this 

 S]5ecies, of v/hich the largest is about 40 m.ra. in latitu-ie and 

 altitude, are at h^nd. It is the only member ^-^ •'■he genus ^lacu 

 nanomia so far recorded in the \7est Indian Tertiaries. '"he gemis 

 at the present time occurs on t'- e Pacific coast of Central Ameri- 



