GEOGRAPHICAL DISTRIBUTION. 37 



Bulimulus mult Hi neat us was introduced from the continent of South 

 America, 1 where it has been found at St. Martha, N. Granada, and at 

 Maracaibo and Pto. Cabello in Venezuela. 



Florida has not only received several of its species from the West 

 Indies, but also from its southern extremity it has contributed in return 

 to the fauna of those islands. From hence, no doubt, Zonites arborens 

 has passed into Cuba and Guadaloupe ; Zonites minuscuhis to Cuba, 

 Jamaica, Porto Rico (Bermuda'?) ; Pupa fallax to Cuba; Vertigo ovata 

 to Cuba; Zonites indentatus to San Domingo'? 



From the various sources indicated above, the southern extremity of 

 Florida has become inhabited by about seventy species of land shells, a 

 number small in comparison with those found in the Cumberland Sub- 

 Region (see p. 33), but large when compared with those found in the 

 great Interior Region. 



In addition to those species apparently originating in the peninsula 

 of Florida and thence spreading over the whole Southern Region, there 

 is found within its limits a number of species confined to the southwest- 

 ern portion of the latter. These seem restricted to the southern part 

 of Texas, which may be considered an offshoot of the Mexican fauna as 

 shown by the presence of the genera characteristic of that country, such 

 as Holospira, Bulimulus, and Gland ina. Within the region, however, 

 are many species peculiar to it, but belonging to the genera charac- 

 teristic of North America, such as Polygyra and Mesodon. It seems, 

 therefore, best to consider Texas as belonging equally to the fauna of 

 North America and of Mexico, being the point where the two overlap. 

 As the limits of the region are ill defined, several species extralimital to 

 the State of Texas are included in the following catalogue of the Texan 

 Region : — 



Glandina Vanuxemensis. Polygyra triodontoidea. 



decussata. Mooreana. 



bullata. tholus. 



Texasiana. hippocrepia. 



Zonites significans. Jacksoni. 



caducus. Ariadne. 



Microphysa incrustata. vultuosa. 



Strobila Hubbardi. Mesodon divesta. 

 Polygyra ventrosula. Roemeri. 



Hindsi. Dorcasia Berlandieriana, 



Texasiana. griseola. 



1 Or from some extinct launa which also accounts for its presence at both points. 



