GASTEROPODA. 



145 



T7/pe, J), lacmiata. PI. X., fig. 13. (== T. delphinus, L.) 



Shell orbicular, depressed ; whirls few, angulated, rugose, or spiny ; aper- 

 ture round, pearly ; peristome continuous ; umbilicus open ; operculum horny, 

 many-whirled. On reefs, at low-water. 



Animal without head-lobes ; sides lobed and cirrated. 



Distr., 20 sp. Red Sea, India, Philippines, China, Australia. 



Fossil, 30 sp. ? Trias ?— Miocene— . Europe. 



Sub-genera. Zioiia, Gray. L. gerviHii. PI. X., fig. 14. Aperture 

 pearly, with a regular, expanded border. Operc. multi-spiral, calcarious. 

 Distr., 6 sp. Cape, India, Philippines, Australia. Fossil, Eocene—. Brit., 

 France. 



Collonia, Gray, 1850. C. marginata. PI. X., fig. 16. Peristome sim- 

 pie. Operc. calcarious, with a spii-al rib on the outer side. Distr., Africa. 

 Fossil, Eocene—. Paris. 



Cyclostrema, Marryat. C. cancellata, PL X., fig. 15. Shell nearly dis- 

 coidal, cancellated, not pearly; apertm-e round, simple; umbilicus wide. 

 Operc. spii-al, calcarious. Distr., 12 sp. Cape, India, Philippines, Australia, 

 Peru. In 5 — 17 fathoms. Serpularia, Roemer, has the whirls smooth and 

 dis-united. Eocene, Paris. 



Adeorbis, Searles Wood. 

 Type, A. sub-carinatus. PI X., fig. 17. 



Shell minute, not nacreous, depressed, few- whirled, deeply umbilicated ; 

 peristome entire, nearly continuous, sinuated in its inner side, and slightly so 

 extenially. Operc. shelly, multi-spiral. 



Distr., W. Indies— China. Low-water to 60 fathoms. 

 Fossil, 5 sp, Miocene — . Brit. 



EuoMPHALUS, Sowerby. 



Ftym., en, wide, and omphalos, umbilicus. 



Syn., schizostoma, Bronn. Maclm-ea, Leseuer. Ophileta, Vanuxem. 

 Platyschisma, INIcCoy. 



Type, E. pentagonalis. PI. X., fig. 18. 



Shell depressed or discoidal ; whirls angular or coronated ; aperture poly- 

 gonal ; umbilicus very large. Operc. shelly, round, multi-spiral (Salter). 



Fossil, 80 sp., L. sil.— Trias. N. America, Em-ope, Australia. 



Sub-genus. Phanerotimts, J. Sby. 1840, E. cristatus, Phil. Carb. lime- 

 stone. Brit. Shell discoidal; whirls separate; outer margin sometimes 

 foliaceous. 



Stomatella, Lam. 



Etym., diminutive of stoma, the aperture. 



Type, S. imbricata. PI. X., fig. 19. 



Shell ear-shaped, regular ; spire small ; aperture oblong, very large and 



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