INSTITUTE OF SCIENCE, PHILADELPHIA. 103 



*Nassa vibex, *Dione (Calliste) gigantea, 



Turbinella regina, * " maculata, 



Vasum horridum, Cardium Floridanum, 



Mazzalina bulbosa, *Cardium magnum, 

 Voluta Floridana, isocardia, 



Mitra lineolata, Hemicardium columba, 



Marginella limatula, *Chama arcinella, 

 *Oliva literata, " crassa, 



* " reticularis, Lucina disciformis, 

 Columbella rusticoides, * " edentula, 

 *Cancellaria reticulata, * " Pennsylvanica, 

 Pleurotoma limatula ? * " Floridana, 

 Conus Tryoni, * " tigerina, 



" Mercati ? Carditamera arata, 



" catenatus ? Area scalarina, 



Strombus Leidyi, " crassicosta, 



* " pugilis, * " lienosa, 

 Cypraea(Siphocypra;a)problematica, " aquila, 

 *Pyrula reticulata, " plicatura, 



*Natica canrena, " (Arcoptera) aviculaeformis, 



* " duplicata, *Pectunculus lineatus, 

 *Crucibulum verrucosum, aratus, 

 Crepidula cymba^formis, Spondylus rotundatus, 



* " fornicata, *Plicatula ramosa, 

 Turritella perattcnuata, Pecten solarioides, 



" apicalis, " comparilis, 



" cingulata, " Mortoni, 



" mediosulcata, * " nodosus, 



" subannulata, * " nucleus, 



*Cerithium atratum ? Anomia Ruffini, 



" ornatissimum, Ostrea meridionalis, 



*Bulla striata, * " Virginica. 

 *Siliqua bidentata, 



The species preceded by an asterisk are living forms. 



It will be seen from the above enumeration that of a total of some 

 eighty-nine species forty-one are still members of the recent fauna, con- 

 stituting forty-six per cent, of the entire number. In addition to these 

 immediate representatives of the recent fauna there are a number of forms 

 which are secondarily representative in the circumstance of being ances- 

 tral, /. e., they are manifestly types from which, through an evolutionary 

 process, a portion of the recent fauna has been derived. The close rela- 

 tion which thus binds together 1 the fauna of the present period with that 



