510 
GEOGRAPHICAL ZOOLOGY. 
[PART IV. 
Family 12. — DITTO RIN1DZE. (9 Genera, 310 Species.) 
Distribution. — The Littorinidse are mostly found on the coasts 
in shallow water ; as the common Periwinkle ( Littorina littorea) • 
They are of world-wide distribution ; but Solarium and Phorus 
are tropical ; while Lacuna, SkeneU, and most species of Rissoa 
are Northern. About 180 species are fossil, ranging from the 
Permian to the Pliocene formations. 
Family 13.— PALITDINIDiE. (4 Genera, 217 Species.) 
Distribution. — The Paludinidm, or River-snails, are all fresh- 
water, and range over the whole world. Paludina (60 sp.), is 
confined to the Northern Hemisphere ; Ampullaria (136 sp.), 
is tropical ; Amphibola (3 sp.), inhabits New Zealand and the 
Pacific Islands ; Valvata (18 sp.), North America and Britain. 
There are 72 fossil species of Paludina and Valvata, in the 
Wealden formation and more recent fresh-water deposits. 
Family 14. — NERITlDiE, (10 Genera, 320 Species.) 
Distribution. — All warm seas, ranging north to Norway and 
the Caspian Sea. Neritina and Navicella inhabit fresh or brack- 
ish waters, the latter confined to the countries bordering the 
Indian Ocean and the islands of the Pacific. There are 80 fossil 
species, from the Trias, Lias, and Eocene formations down to 
recent deposits. 
Family 15. — TURBINIDZE, (10 Genera, 425 Species). 
Distribution. — The genus Trochus (200 sp.) has a world- wide 
range, but the other genera are mostly tropical, and are most 
abundant in the Indian and Pacific Oceans. There are more 
than 900 fossil species, found in all parts of the world, from the 
Lower Silurian to the Tertiary formations. 
