2 Observations on the Terrestrial 



has freely sent me all the works at his disposal, furaishing any de- 

 sired intelligence on the subject, and by frequent correspondence 

 has decided many perplexing questions concerning synonymy. 



Having most unfortunately parted with my own collections, the 

 results of diligent labor for several years, I have depended greatly 

 on the valuable collections of Adjutant John M. Gould and Mr. 

 Charles B. Fuller, of Portland, who placed all their material 

 entirely at my disposal ; to these gentlemen I wish to tender my 

 sincere thanks. I am also indebted to the Rev. E. C. Bolles, 

 of Portland, for valuable assistance in numerous microscopical . 

 examinations. My thanks are due to Temple Prime, Esq., of New 

 York city, George W. Try on, Jr., of Philadelphia, and A. E. Verrill, 

 of the Museum of Comparative Zoology at Cambridge, for numerous 

 acts of kindness. 



Through the generosity and kindness of W. G. Binney, I have 

 had the pleasure of examining Albers' sj'stematic arrangement 

 of the Helicidae.* 



I have adopted the sub-generic names of AJbers, as far as it 

 could be done without open Adolation of the natural characters of 

 the animal. In many cases, however, I have made alterations in 

 his arrangement, proposing at the same time not only new genera, 

 but also several sub-families.t 



- Nothing can be more artificial than a classification of moHusca 

 based on the shell alone, or even on any single organ or portion 

 of the animal. Now, true classification is not artificial ; it is the 

 revelation of a natural order. All minor peculiarities j^lay their 

 part only in the grand whole, and therefore we have no Tight to 

 cull out special points here and there for the arbitrary establishment 

 of convenient groupings. In the following synoptical table I have 

 grouped the species together under certain generic, sub-family.^ 



* Der Heliceen. Leipsic, 1860, 2d Ed. by Von Martens. 



t To -write oTit the synonymy of the species here presented would reqtrire a special 

 study, and all the conchological works of this country and of Europe at one's command, in. 

 order to do it properly. I have had neither this opportunity nor desire, and have eonoiuded, 

 to leave this part of the work to other hands. So long as the name of the original describer 

 of a species attemls the shell, no confusion need be caused. The species " Labyrinthfca. 

 Say", will always be known, v/hether it be Helix, Mesodon, Anchistoma, or Strobila; and 

 for this reason t have retained the name of the original describer of the species. 



