266 MANUAL OF THE MOLLUSCA. 



granulated ; lip thickened internally, and grooved ; columella 

 toothed, more or less prominently and irregularly ; operculum 

 horny, many-whorled. 



Distrihution, 13 species ? West Africa, Eed Sea, India, 

 Australia. 



Fossil (included with trochus), Devonian — . Eifel. 



Delphinula (Eoissy), Lam. 



Etymology, diminutive oi delpliinus, a dolphin. (= Cyclostoma, 

 Gray !) 



Type, D. laciniata. PI. X., Fig. 13. (= T. delphinus, L.) 



Shell orbicular, depressed ; whorls few, angulated, rugose, or 

 spiny ; aperture round, pearly ; peristome continuous ; 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 ? — Miocene — . Europe. 



Suh-genera. Liotia, Gray. L. gervillii. PI. X., Fig. 14. 

 Aperture pearly, with a regular, expanded border ; operculum 

 multi-spiral, calcareous. 



Distribution, 6 species. Cape, India, Philippines, Australia. 



Fossil, Eocene — . Britain, France. 



Collonia, Gray, 1850. C. marginata. PI. X., Fig. 15. 

 Peristome simple ; operculum calcareous, with a spiral rib on 

 the outer side. 



Distribution, Africa. 



Fossil, Eocene — . Paris. 



Cyclostrema, Marryat. C. cancellata, PI. X., Fig. 16. 



Shell nearly discoidal, cancellated, not pearly ; apertui'O 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. 



Tyi^e, Euomphalus 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. PI. X., Fig. 17. 



Shell minute, not nacreous, depressed, few-whorled, deeply 

 umbilicated ; peristome entire, nearly continuous, situated in 



