292 MANUAL OF THE MOLLUSCA. 



Zua, Leacli. Z. lubrica, PL XII., Fig. 14 



Shell polislied, columella slightly truncated. 6 species. 



Azeca, Leacli. A. tridens, PI. XII., Pig. 15. 



Shell polislied, peristome thickened and toothed. 4 Hiring 

 species. 



Distribution, 1,120 species. Universally distributed. 



Fossil, 30 species. Eocene — . Europe, St. Helena, Australia, 

 "West Indies. 



B. Ouadalujpensis occurs in modern limestone, with human 

 remains. 



AcHATiNA, Lamarck. Agate-shell. 



Ty^pe, A. variegata, PI. XII., Fig. 22. 



Synonyms, Cochlitoma, Per. Columna, Perry. Subulina 

 (octona). Beck. Liguus (virgineus), Montf. Cionella (acicula), 

 Jeffreys. 



Shell imperforate, bulimiform ; columella twisted, and trun- 

 cated in front ; aperture oval, angular above ; peristome simple, 

 acute. 



Animal snail-like. The great African Achatinse are the 

 largest of all land-snails, attaining a length of eight inches ; 

 their eggs exceed an inch in length, and have a calcareous 

 shell. 



Distribution, 370 species. Europe, Africa, Asia, and tropical 

 America. 



Fossil, 19 species. Eocene — . Europe and St. Helena. 



Sub-genera. Olandina (voluta), Schum. (Oleacina, Bolten; 

 Polyphemus, Montf.) 



Shell oblong, fusiform ; aperture narrow, elliptical. 



Animal twice as long as the shell ; eye tentacles deflected at 

 the tips, beyond the eyes ; vibracula much shorter, also deflected; 

 lips elongated, tentacular. Frequents low and moist situations ; 

 in confinement one refused vegetable food, but ate another 

 snail. (Say.) 186 species. West Indies, Central America, 

 Mexico, Florida. 



Fossil. Eocene — . Olandina costellata. Isle of Wight. (F. 

 Edwards.) 



Achatinella (vulpina), Sw. (Helicteres, Per.) Columella 

 twisted into a strong, tooth-like fold. Sandwich Islands 25, 

 Mariannes 2, Ceylon 1. 



Pupa, Lamarck. Chrysalis-shell. 



Type, P. uva. PI. XII., Fig. 16. 

 Synonym, Torqailla fiuniperi), Studer. 



