246 IMANtJAL OF THE MOLLTJSCA. 



Strttthiolaeia, Lam. 



Etymology J struthio, an ostricli (-foot), from the form of its 

 aperture. 



Type, S. straminea, PL IV., Pig. 6. 



Shell turreted ; whorls angular ; aperture truncated in front ; 

 columella very oblique ; outer lip prominent in 

 the middle, reflected and thickened in the adult ; 

 inner lip callous, expanded ; operculum claw- 

 shaped, curyed inwards, with a projection from 

 the outer, concave edge (Pig. 101). 



Animal with an elongated muzzle ? tentacles 

 cylindrical ; eye-pedicels short, adnate with the 

 tentacles, externally: foot broad and short. 



Fig. 101. ,^. ' -^ 



Operculum of (iliener.) 



titruthiQiaria, Distrihution, 5 species. Australia and New 

 Zealand, where alone it occurs sub-fossil. 



Family IV. — Melaniad^. 



Shell spiral, turreted ; with a thick, dark epidermis ; aperture 

 often channeled, or notched in front ; outer lij) acute ; operculum 

 horny, spiral. The spire is often extensively eroded by the 

 acidity of the water in which the animals live. 



Animal -with, a broad non-retractile muzzle ; tentacles distant, 

 subulate ; eyes on short stalks, united to the outer sides of the 

 tentacles ; foot broad and short, angulated in front ; mantle- 

 margin fringed ; tongue long and linear, with a median and 3 

 lateral series of hooked multi-cuspid teeth. Often viviparous. 

 Inhabiting fresh- water lakes and rivers throughout the warmer 

 parts of the world. 



Melania, Lam. 



Ehjmology, onelania, blackness {irom. melas). 



Type, M. amarula. PL VIIL, Pig. 25. 



Synonyms, Thiara, Megerle. Pyrgula, Crist. 



Shell turreted, aj)ex acute (unless eroded) ; whorls orna- 

 mented with strise or spines ; aperture oval, pointed above ; 

 outer lip sharj), sinuous; operculum subspiral. PL VIIL, 

 Fig. 25.* 



DistrUmtion, 361 species. South Europe, India, Philippines, 

 Pacific Islands. Distinct g'rouj)s in the southern States of 

 North America. 



