X PREFACE. 



More recently, the last named gentleman has collected, 

 and arranged, an extensive herbarium of Hysterophyta (he 

 Fungi), a large proportion of which were in the county. 



Thirty years ago, Dr. E. Michener collected, and pre- 

 served, specimens of most of the Mammalia, Birds, and Rep- 

 tiles, known to inhabit Chester County. More recently, 

 Vincent Bernard successfully occupied the same field. These 

 important collections have mostly been placed in the Cabinet 

 of Swarthmore College. 



The proverbial richness of our county, in rare and valuable 

 minerals, is amply sustained, and illustrated, by the splendid 

 Mineralogical Cabinets of William W. Jefferis, and other 

 savans. 



Last, but not least; in 1853, Dr. William D. Hartman 

 prepared "A Descriptive Catalogue of the Terrestrial, and 

 Fluviatile, Testaceous Mollusks, of Chester County" con-, 

 taining fifty-nine species. The cost of printing prevented 

 the publication at that time of more than "A Classified 

 Catalogue ' ' of the species. 



More than a duplication of the number of species then 

 known to inhabit the county, and the progressive improve- 

 ments in classification and nomenclature, have rendered 

 that Catalogue obsolete, and imperiously calls for one more 

 in accordance with the advanced state of the science. Our 

 wish, and desire, is to supply this want. And we entertain 

 the hope that our effort will be received with indulgence; 

 and, that it may serve to diffuse a taste for, and facilitate the 

 study of, this interesting branch of our rich Fauna Cestrica 

 among our young naturalists. 



A few extra-limital species have been inserted, from the 

 eastern slope of the mountain range, in our State ; and which 

 may yet occur within this county. 



