PREFACE. 



The vast abundance of fossil shells which characterize the 

 the Tertiary formations throughout the world, render it neces- 

 sary to devote particular works to their elucidation, in which 

 accurate figures may enable us to study and compare them un- 

 der every variety of geographical distribution. ^ 



In Europe they have received that attention they eminently 

 deserve in a Geological point of view, and particularly those of 

 the environs of Paris have been accurately figured and des- 

 described, while the greater part of the analogous American 

 fossils remain unpublished. The shells peculiar to the Green 

 formation in the United States have been illustrated in a very 

 satisfactory manner by Dr. S. G. Morton, and it now remains 

 to -publish those of the Tertiary beds, in order to complete the 

 works of reference necessary to the student in Geology. 



The greater part of the deposits in question evidently agree 

 with the Upper Marine of Conybeare and Phillips; but fossils 

 analogous to those of the London Clay or Calcaire Grossier 

 also occur in this country, and are found at Fort Claiboure in 

 Alabama, as well as in some parts of Maryland and Virginia. I 

 have, however, examined in situ those of James river, in Vir- 

 ginia, which Mr. Finch has referred to as indicative of the 

 London clay, but. they embrace too many recent species, and 

 are entirely deficient in- the characteristic genera, as Cerithivw, 

 Rostellaria, &c. 



It is a remarkable fact, that so%many species still existing 

 upon the coast should be mixed with others, known only in a 

 fossil state, and as they are all littoral shells, there is no pro- 

 bability that the latter exist in deep water. It is true that a 

 single living specimen of Cerithium giganteum, a very abund- 

 ant fossil in the vicinity of Paris, was taken in deep water, off 

 the coast of New Holland ; but of such genera as Balctnus, Os- 

 trea, Panopea, &c. we would expect to find all the recent spe- 

 cies, either inhabiting shallow water, or cast ashore by storms. 



[20] 



