A MANUAL OF AMERICAN LAND SHELLS. 31 



Pupa fallax. Vertigo ovata. 



rupicola. Succinea avara, 

 corticaria. ovalis. 



Vertigo milium. 



Tebeimopliortis GaroUniensiSy T. dorsalis, aucl Limax campestris proba- 

 bly have also come down from Post-pleiocene times. From their nature 

 they could leave no record of their presence in the " bluffs." 



There are also found in the Interior Region several forms of Succinea 

 of doubtful specific value, which have been described as — 



Succinea retusa. Succinea aurea. 



Orosvenori. Mooresiana. 



lineata. 



The following is a complete list of those species of the Interior Eegion 

 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 Eegion, described on p. 27, 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 albolahris. 



inornatus. thyroides. 



suppressus. Pwpa pentodon. 



indentatus: fallax. 



arboreus. armifera. 



minusGulus. contracta. 



Limax campestris. rupicola. 



Patula alternata. corticaria. 



Helicodiscus lineatus. Vertigo milium. 

 Strohila labyrinthica. ovata. 



Stenotrema hirsutum. Succinea avara. 



monodon. ohliqua. 



Triodopsis palUata. Tebennophorus Caroliniensis. 

 tridentata. dorsalis. 



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

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

 latitudes east 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 



