342 



THE NEOTROPICAL REGION 



L. Baikal. BitJiynia^ absent from the Eastern States, is repre- 

 sented by two species. The general indications are in favour of 

 the Californian fauna having migrated from an Old World source 

 after the upheaval of the Sierras ; the American fauna, on the 

 other hand, is purely indigenous, with no recent Old World 

 influence at all. 



Land Mollusca of the Nearctic Region 



Glandina . . 



4 



Pristiloma . . 2 



Praticola . 



. 2 



Strobila . . . 



2 



Selenites . . 



6 



Tebennophorus 4 



Glyptostoma 



. 1 



Pupa . . . . 



18 



Limax . . . 



4 



Ariolimax . . 6 



Mesodon . 



. 27 



Vertigo . . . 



8 



Vitrina . . . 



4 



Prophysaon . 2 



Stenotrema 



. 11 



Holospira . . 



2 



Vitrinozonites 



1 



Hemphillia . 1 



Triodopsis . 



. 21 



Cionella . . 



1 



Mesomphix 



15 



Binneya . . 1 



Polygyra . 



. 23 



Bulimulus . . 



6 



Hyalinia . . 



22 



Patula ... 18 



Polygyrella 



. 2 



Macroceramus 



1 



Conulus . . 



1 



Punctum . . 2 



Gonostoma 



. 1 



Succinea . . 



21 



Gastrodonta . 



9 



Arionta . . 20 

 Helicina 



Vallonia . 

 . . 2 



. 1 



Vaginulus . . 



1 



F. The Neotropical Region 



4 



The land Mollusca of the Neotropical Region stand in com- 

 plete contrast to those of the Nearctic. Instead of being scanty, 

 they are exceedingly abundant; instead of being small am 

 obscure, they are among the largest in size, most brilliant ii 

 colour, and most singular in shape that are known to exist. Ai 

 the same time they are, as a whole, isolated in type, and exhibit 

 but little relation with the Mollusca of any other region. 



The most marked feature is the predominance of the peculiar, 

 genera Bulimus and Bulimulus^ the centre of whose develop-J 

 ment appears to lie in Peru, Ecuador, and Bolivia, but whicM 

 diminish, both in numbers and variety of form, in the easterir 

 portion of the region. In the forests of Central America, 

 Venezuela, and Ecuador, and, to a lesser degree, in those of Peru 

 and Brazil, occurs the genus Orthalicus^ whose tree-climbing 

 habits recall the Oochlostyla of the Philippines. These three 

 groups of bulimoid forms constitute, as far as the mainland is 

 concerned, the preponderating mass of the land Mollusca. Helix 

 proper is most strongly developed in the Greater Antilles, which 

 possess several peculiar groups of great beauty. In Central 

 America Helix is comparatively scarce, but in the northern 

 portions of the continent several fine genera (^Lahyrinthus^ 



