266 MANUAL OF THE MOLLUSCA. 
granulated ; lip thickened internally, and grooved; columella 
toothed, more or less prominently and irregularly ; operculum 
horny, many-whorled. 
_ Distribution, 138 species? West Africa, Red Sea, India, 
Australia. 
Fossil (included with trochus), Deyvonian—. Hifel. 
DELPHINULA (Roissy), Lam. 
Etymology, diminutive of delphinus, a dolphin, (= Cyclostoma, 
Gray !) 
Type, D. laciniata. Pl. X., Fig. 18. (= T. delphinus, L.) 
Shell orbicular, depressed ; sek few, angulated, rugose, or 
spiny; aperture round, pearly; peristome cna um- 
bilicus open ; operculum horny, many-whorled. On reefs at 
low water. 
Animal without head-lobes; sides lobed and cirrated. 
Distribution, 70 species. Red Sea, India, Philippines, China, 
Australia. 
Fossil, 30 species? Trias ?—Muiocene—. Europe. 
Sub-genera. Lotia, Gray. L. gervilli. PL X., Fig. 14. 
Aperture pearly, with a regular, expanded border; operculum 
multi-spiral, calcareous. 
Distribution, 6 species. Cape, India, Philippines, Australia. 
Fossil, Hocene—. Britain, France. 
Collonia, Gray, 1850. C. marginata. Pl. X., Fig. 13. 
Peristome simple; operculum calcareous, with a spiral rib on 
the outer side. 
Distribution, Africa. 
Fossil, Hocene—. Paris. 
Cyclostrema, Marryat. C. cancellata, Pl. X., Fig. 16. 
_ Shell nearly discoidal, cancellated, not pearly ; aperture round, 
simple; umbilicus wide ; operculum, spiral, calcareous. 
Distribution, 12 species. Cape, India, Philippines, Australia, 
Peru. In 5—17 fathoms. 
Serpularia, Roemer, has the whorls smooth and disunited. 
Type, Huomphalus Serpula, Kon. Carb. Belgium. 
Crossostoma, Morris and Lycett. Columella toothed when 
young, concealed by callus in the adult. 2 species, Great 
oolite. 
ADEORBIS, Searles Wood. 
Type, A. sub-carinatus. Pl. X., Fig. 17. 
Shell minute, not nacreous, depressed, few-whorled, deeply 
umbilicated ; peristome entire, nearly continuous, situated in 
