TRANSACTIONS OF WAGNER 



774 



' ' TERTIARY FAUNA OF FLORIDA 



obviously of different function. The genus is a puzzle and cannot as yet be 

 safely united with any other. Diploschi.za Conrad, however, appears to be 

 founded on a broken valve of an ordinary Aiiouiia. It is impracticable to 

 attempt here a revision or discussion of the names which have been applied 

 to exotic fossils apparently related to this group, as the material is wanting, 

 and few of them have been intelligently studied in the light of the anatomical 

 relations of the recent forms. 



In 1870 Stoliczka (Cret. Pelec. India, p. 451), misled by an imperfect 

 knowledge of its synonymic status, proposed for Epliippuivi (Bolt.) Gray the 

 name Plaainema, which falls into synonymy. 



It seems to the writer that the absence of any foramen and the perma- 

 nently byssiferous habit of Placenta generically distinguish it from all the 

 foraminiferous Anoiniidce. Its arenaceous habitat is also different from all the 

 rest. 



Placunanomia as typified by P. Ciunhigii seems also a good genus. 



The list, omitting doubtful forms and unstudied exotics, will stand about 

 as follows : 



1. Byssal scars absent or obsolete. 



Genus Placenta. Type P. orbicularis Retzius. 

 Genus Ephippium. Type E. sella Gmelin. 

 Genus Carolia. Type C. placunoides Cantraine. 

 Section Wakullina. Type C. floridana Dall. 



2. A single conspicuous byssal scar on the disk. 



A. Adult foramen closed ; hinge armate. 

 Genus Placunanomia. Type P. Cuiniiigii Broderip. 



B. Adult foramen small ; hinge unarmed. 

 Genus Pododesinus. Type P. rndis Broderip. 



0. Adult foramen large ; hinge unarmed. 

 Section Moiiia. Type P. inacrosckisina Deshayes. 



3. Two byssal scars on the disk ; hinge unarmed ; foramen open. 



A. Main byssal scar largest ; foramen ample. 

 Genus Anoviia. Type A. ephippium Linne. 



B. Adductor scar larger than those of the byssus; foramen small. 

 ? Section Patro. Type A. clyros Gray. 



0. Main byssal scar distant from the two others. 

 Section ^Enigma. Type A. cenigmatica Jonas. 



