GASTEROPODA. 289 



Distribution, including the gub-genera, above 1,600 species 

 (several hundred species are ue described). World-wide ; rang- 

 ing northward as far as the limit of trees, and southward to 

 Tierra-del-Fuego, but most abundant by far in warm and humid 

 climates. M. D'Orbigny obseived 6 species at elevations ex- 

 ceeding 11,000 feet in South America, and Layard found H. 

 gardeneri at the height of 8,000 feet in Ceylon. The species of 

 tropical and southern islands are mostly peculiar. Several of 

 the smaller British species, and even the large garden-snail {H. 

 aspersa), have been naturalised in the most remote colonies. 

 The Neapolitans and Brazilians eat snails. 



Fossil species about 200. Eocene — . Europe. 

 Sections : Acavus, Montf. Shell imperforate. H. haemastoma, 

 PL XII., Eig. 1. 



Geotrochus (lonchostoma) Hasselt, Trochiform, flat beneath. 

 Polygyra, Say. Depressed, many-whorled. H. polygyrata, 

 PI. XIL, Eig. 2. 



Tredopsis, Eaf. Aperture contracted by tooth-like projections. 

 H. Hirsuta, PL XIL, Eig. 5. 



CarocoUa, Lam. Peristome continuous. H. lapicida, PL XIL, 

 Tig. 3. 



Suh-genera. Anastoma, Eischer. (Tomigerus, Spix.) H. 

 ^lobulosa, PL XIL, Eig. 4. Aperture of adult turned up- 

 wards, ringent ; 4 species. BrazL. 



Hypostoma (Boysii), Albers, is a minute Indian snail, in which 

 the aperture is similarly distorted. 



Lychnus (Matheroni, Peq.) has a similar shell, but no apertural 

 teeth ; 3 species occur in the Eocene Tertiary of South Erance. 

 Streptaxis, Gray. H. contusa, PL XIL, Eig. 6. Sub-globose, 

 lower whorls receding from the axis of the upper ; 34 species. 

 Brazil, West Africa, Mascarene Islands, South Asia. 



Sagda, Beck. H. epistylium, PL XIL, Eig. Y. Imperforate, 

 globosely conoid, close-whorled, aperture lamellate within, lip 

 sharp ; 3 species. Jamaica. 



Proserpina (nitida), Guilding. Shell depressed, shining, 

 callous beneath ; aperture toothed inside ; peristome sharp. 

 Distribution, 6 species. Jamaica, Cuba, Mexico. 

 Fossil, 'Eocene — . Isle of Wight. (E.Edwards.) 

 Helicella, Lam.* Type, H. cellaria, PL XIL, Eig. 8. Shell 

 thin, depressed; peristome sharp, not reflected. Lingual edge- 

 teeth aculeate. 110 species. 

 Stenopus (cruentatus), Guild. 



* For this group Dr. Gray formerly employed the name Zonites, given origintJI^ by 

 Montfort to Helix Algira; in his later works he adopts ITeliceUa. 



O 



