MUSEUM OF COMPARATIVE ZOOLOGY. 211 



Tlie following species are peculiar to this Sub-Region : — 



Zonites kopnodes. Helix spinosa. 



subplanus. labrosa. 



sculptilis. Edgariana. 



Elliotti. Edvardsi. 



demissus. barbigera. 



capsella. maxillata. 



lasmodon. Rugeli. 



Patula Cumberlandiana. introferens. 



tenuistriata. ? Clarki. 



Helix fastigans. Christyi. 



Troostiana. Wheatleyi. 



Hazardi. Downieana. 



Of these, several have spread beyond the limits given above for 

 the Sub-Region. Thus, Zonites lasmodon and Helix spinosa have been 

 found in Northern Alabama. Helix Hazardi has also spread into North- 

 ern Alabama, and equally into Georgia and Kentucky. Helix labrosa. 

 and Helix Edgariana in Alabama, and in one case have been collected in 

 Arkansas. Helix barbigera, Helix maxillata, and Zonites kopnodes 

 have found their way into Alabama and Georgia; Helix Clarki into 

 Georgia. Zonites subplanus has been found even in Pennsylvania, having, 

 no doubt, crept along the mountain chain ; but no other of the species of 

 the Cumberland Sub- Region has been found as far north, excepting Z. 

 demissus. This last-named species is found in a highly developed state 

 in Eastern Tennessee, and has extended into Western Pennsylvania, 

 North Carolina, Georgia, Alabama (near Mobile), and Arkansas in a 

 much dwarfed condition. 



If to the twenty-four species catalogued above as peculiar to the Sub- 

 Region are added the sixty-six species which inhabit it as a portion of 

 the Interior Region (see p. 209), it will be seen that in the Cumberland 

 Sub-Region we find the largest number of species of any other portion of 

 North America. The Sub-Region is equally prolific in individuals, and 

 the individuals are highly developed. These facts are partially explained 

 by the nature of the country. Low mountains, thickly shaded, well 

 watered, and with a genial climate and proper soil, offer in their thickets 

 and ravines innumerable safe breeding-grounds for the land shells.* 



■© o* 



* Sec A. Binney, Terr. Moll. U. S , I. pp. 122, 123. Being less adapted for culti- 

 vation than the balance of Eastern North America, we may hope for the preservation 



