GASTEROPODA. 265 
Distribution, 200 species. World-wide. Low water to 15 
fathoms; the smaller species range nearly to 100 fathoms. 
Fossil, 361 species. Devyonian—. Europe, North America, 
Chili. 
Sub-genera. Pyranvis, Chemn., Tr. obeliscus. Pl. X., Fig. 6. 
Columella contorted, forming a slight canal. 
Gibbula, Leach. Tr. magus, Britain. 
Shell depressed, widely umbilicated ; whorls tumid. Head- 
lobes largely developed; lateral cirri, 3. 
Enida, Adams. 3 species, Japan. 
Margarita, Leach. Tr. helicinus. Pl. X., Fig. 7. 
Shell thin ; cirri, 5 on each side. 
Distribution, 17 species. Greenland, Britain, Falkland 
Islands. Near low water, under stones and sea-weed. 
Elenchus, Humphrey (= Canthiridus, Montfort) H. iris. Pl. 
X., Fig. 8. Smooth, thin, imperforate, with a prominent base. 
Australia, New Zealand. /. Jris scarcely differs in form from 
Tr. zizyphinus; #. badius is uke a pearly phasianella; and 
EL. varians (bankivia, Menke) would be called a chemnitaia, if 
fossilised. Pl. X., Fig. 9. 
Alcynus, Adams. 2 species, Japan. 
Minolia, Adams. 1 species, Japan. 
Turcica, Adams. 1854. 
Vitrinella, C. B. Adams, 1850. Shell minute, hyaline, 
turbiniform, umbilicated; aperture large, orbicular. 
Distribution, 18 species. West Indies (5), Panama. 
Photinula, H. and A. Adams, 1855. Shell heliciform ; spire 
somewhat acute. 
RoTELLA, Lamarck. 
Etymology, diminutive of rota, a wheel. 
Synonym, Helicina, Gray. 
Lype, R. vestiaria. Pl. X., Fig. 10. 
Shell lenticular, polished; spire depressed; base callous; 
lingual teeth 13; uncini numerous, sub-equal. 
Distribution, 15 species. India, Philippines, China, New 
Zealand. 
Monoponta, Lam. 
Hiymology, monos, one, and odous (odontos), a tooth. 
Synonyms, Labio, Oken. Clanculus. Montfort, Olivia, Risso. 
Types, M. labeo. Pl. X., Fig. 21. M. pharaonis. Pl. X., 
Fig. 12. 
Stell turbinated, few-whorled ; whorls spirally grooved and 
N 
