PREFACE 



r I "" 1 IE present continuation of the work on our Southeastern Tertiary fauna 

 carries the text so far that it seems certain that another part will conclude 

 the work. It includes a large part of the Teleodesmacea, but it was found that 

 the family Veneridae was too extensive to he finished without unduly delaying 

 the publication of the manuscript already completed, and the discussion of 

 that group is therefore deferred until the next instalment is printed. 



The present part reviews the nomenclature of several groups in which 

 great confusion had reigned, and their revision, it is hoped, will be useful to 

 students both of fossil and recent shells. A very large number of hitherto 

 unrecognized species are here first described and figured. 



I have been, as heretofore, under obligations to the authorities of the 

 Smithsonian Institution, the National Museum, and the Director of the United 

 States Geological Survey for essential facilities for study and research without 

 which this work could not have been carried on; to Mr. Joseph Willcox and 

 other officers of the Wagner Free Institute of Science for the most liberal 

 encouragement and assistance in the gathering and illustration of material ; 

 and to Dr. H. A. Pilsbry and the authorities of the Academy of Natural 

 Sciences of Philadelphia for courtesies which they have freely rendered. To 

 numerous correspondents I am also under serious obligations for information 

 furnished and specimens submitted for comparison and study, among whom 

 I cannot refrain from mentioning Mr. E. A. Smith, of the British Museum, 

 and M. Maurice Cossmann, of Paris, France, whose courtesy has been un- 

 failing and unlimited. 



WILLIAM H. DALL. 



