| Glandina | 4 |
| Selenites | 6 |
| Limax | 4 |
| Vitrina | 4 |
| Vitrinozonites | 1 |
| Mesomphix | 15 |
| Hyalinia | 22 |
| Conulus | 1 |
| Gastrodonta | 9 |
| Pristiloma | 2 |
| Tebennophorus | 4 |
| Ariolimax | 6 |
| Prophysaon | 2 |
| Hemphillia | 1 |
| Binneya | 1 |
| Patula | 18 |
| Punctum | 2 |
| Arionta | 20 |
| Praticola | 2 |
| Glyptostoma | 1 |
| Mesodon | 27 |
| Stenotrema | 11 |
| Triodopsis | 21 |
| Polygyra | 23 |
| Polygyrella | 2 |
| Gonostoma | 1 |
| Vallonia | 1 |
| Strobila | 2 |
| Pupa | 18 |
| Vertigo | 8 |
| Holospira | 2 |
| Cionella | 1 |
| Bulimulus | 6 |
| Macroceramus | 1 |
| Succinea | 21 |
| Vaginulus | 1 |
| Helicina | 2 |
F. The Neotropical Region
The land Mollusca of the Neotropical Region stand in complete contrast to those of the Nearctic. Instead of being scanty, they are exceedingly abundant; instead of being small and obscure, they are among the largest in size, most brilliant in colour, and most singular in shape that are known to exist. At 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 development appears to lie in Peru, Ecuador, and Bolivia, but which diminish, both in numbers and variety of form, in the eastern 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 Cochlostyla 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 (Labyrinthus, Isomeria, Solaropsis) occur, which disappear altogether towards the south.
Carnivorous land Mollusca are, so far as Central America is concerned, more highly developed than in any other quarter of the world, particularly in the genera Glandina and Streptostyla. These genera also penetrate the northern portions of the continent, Glandina reaching as far as Ecuador, and Streptostyla as far as Peru. The Greater Antilles have also characteristic forms of these genera. Streptaxis is tolerably abundant all over tropical South America, and is the one pulmonate genus which shows any affinity with the African fauna.
The slugs are exceedingly scarce. Vaginula occurs throughout, and is the only genus in any sense characteristic.
Clausilia, in the sub-genus Nenia, occurs along the Andean chain from the extreme north (but not in Central America) as far south as Bolivia. It has in all probability made its way into S. America in exceedingly remote ages from its headquarters in Eastern Asia. No species survives in N. America, and a single straggler is found in Porto Rico. The genera Macroceramus, Cylindrella, and Strophia, are characteristic West Indian forms, which are only slightly represented on the mainland. Homalonyx, a curious form akin to Succinea, is peculiar to the region.
Fig. 228.—Homalonyx unguis Fér., Demerara. sh, Shell (shown also separate); p.o, pulmonary orifice.
Land operculates attain a most extraordinary development in the Greater Antilles, and constitute, in some cases, nearly one-half of the whole Molluscan fauna. Several groups of the Cyclostomatidae find their headquarters here, and some spread no farther. On the mainland this prominence does not continue. West Indian influence is felt in Central America and on the northern coast district, and some Antillean genera make their way as far as Ecuador. The whole group entirely disappears in Chili and Argentina, becoming scarce even in Brazil.