GASTEEOrODA. 



291 



teeth, like helix; S. j^utris has 50 rows of 65 teeth, each. 

 (Thomson.) Inhabits damp places, but rarely enters the water. 



Distribution, 155 species. World-wide. 



.Fossil, 7 species. Eocene. Britain. 



Sub-genus. Omalonyx, D'Orbigny. 0. unguis, PL XII., 

 Fig. 24. 



i:i]iell oval, convex, translucent, spii-e nearly obsolete, margins 

 sharp. 



Animal IdiT^e, slug-like; shell placed on the middle of tho 

 back, with the mantle slightly reflected upon it all round. 



Distribution, 2 species. Bolivia, Juan Fernandez. 



BuLiMUS, ScopoH. 



Etymology ? BouUmos, extreme hunger (in allusion to its 

 voracity !). 



Synonym, Bulinus, Brod. (not Adans). 



Type, B. oblongus, PL XII., Fig. 10. 



Shell oblong or tuiTeted ; aperture with the longitudinal 

 margins unequal, toothless or dentate ; columella entire, revolute 

 externally or nearly simple ; peristome simple or expanded 



Animal like Hebx:. B. ovatus attains a length of six inches, 

 and is sold in the market of Eio ; it 

 oviposits amongst dead leaves, the eggs 

 have a brittle shell, and the young when 

 hatched are an inch long. (See p. 44, 

 Fig. 31.) 



Sections. Odontostomiis (gargantuus), 

 Beck, aperture toothed. 13 species. 

 Brazil. 



Pachyotis, Beck (Caprella, Guild.), 

 Fig. 123.* 



Partula, Fer. P. faba, PL XII., 

 Fig. 13, Tahiti. 26 species. Asiatic, 

 Australian, and Pacific Islands, South 

 America. The animal is ovoviviparous. 



Gibbus [Lyon net ianus) Montf. 



Shell hump-backed. Mauritius, 2 

 species. 



Bulimulus, Leach. B. decoUatus, PL 



XII. 



Fig. 12 ^ 



Figs. 11 and 12. 



Shell small, hp acute. Above 300 species. England, 3 species. 



* Fi{:. 123. Bulimxis auris-vu'pina, Chemn. The great extinct land-snail of St. 

 Hel.'.aa; fr -m a specimen presented by Chas. Darwin, Esq. See "Journal of a Voyage 

 rtuuvl the World." 



02 



