GEOGRAPHICAL DISTRIBUTION. 31 



which have spread beyond it by passing the barriers of the Appalachian, 

 chain, and are now found over New England and the whole southern 

 extension of the Northern Region, described on p. 26, as well as over 

 the whole Southern Region. They may therefore be said to inhabit 

 all of the Eastern Province. 



Macrocyclis concava. Triodopsis fallax. 



Zonites fuliginosus. Mesodon albolabris. 



inornatus. thyroides 



suppressus. Pupa pentodon. 



indentatus. fallax. 



arboreus. armifera. 



minusculus. contracta. 



Limax campestris. rupicola. 



Patula alternata. corticaria. 



Helicodiscus lineatus. Vertigo milium. 

 Strobila labyrinthica. ovata. 



Stenotrema hirsutum. Succinea avara. 



monodon. obliqua. 



Triodopsis palliata. Tebennophorus Caroliniensis. 



tridentata. Pallifera dorsalis. 



Mesodon Sayii and M. dentifera have spread into New England only 

 from the Interior Region. They have not been found in more southern 

 latitudes on the Atlantic slopes of the Appalachian chain, nor in the 

 Southern Region. 



The geographical range of these species is very great, forming one 

 of the most striking features of the North American fauna. Still more 

 widely distributed are those minute species which have been mentioned 

 above as spreading southwardly from the Northern Region equally on 

 both sides of the Sierra Nevada and Rocky Mountains. These species 

 may be said to inhabit the w r hole continent of North America as far 

 south as Mexico. The range of some is still greater. Thus, Zonites 

 minusculus has been found from British Columbia to Labrador on the 

 north, to Yucatan and Florida on the south, and still farther in Cuba, 

 Jamaica, Porto Rico, and Bermuda. Strobila labyrinthica also is found 

 over all Eastern North America, and perhaps in Mexico (as H. Strebeli, 

 see Fischer and Crosse, Moll. Mex. et Gnat., 267). It is also by some 

 considered identical with an Eocene fossil of France and England. (See 

 below.) Zonites arboreus ranges from Labrador to New Mexico, and in 

 Nevada and California, and from British Columbia to Florida, Cuba, and 

 Guadaloupe. Vertigo ovata is found from Maine to Mexico and in Cuba. 



The character of the soil and climate, with, perhaps, the gradual ele- 

 vation, is such as to render the land shells rare, if not quite extinct, 



