GASTEROPODA. 145 



Type, D. laciniata. PL 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. Liotia, Gray. L. gervillii. 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. PL X., fig. 16. Peristome sim- 

 ple. Operc. calcarious, with a spiral 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 ; aperture round, simple ; umbilicus wide. 

 Operc. spiral, calcarious. Distr., 12 sp. Cape, India, Philippines, Australia, 

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

 dis-united. Eocene, Paris. 



ADEOKBIS, Searles Wood. 



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



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

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

 externally. Operc. shelly, multi-spiral. 



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



Fossil, 5 sp. Miocene . Brit. 



EUOMPHALUS, Sowerby. 



Etym., eu, wide, and omphalos, umbilicus. 



Syn., schizostoma, Bronn. -Maclurea, Leseuer. Ophileta, Vanuxem. 

 Platyschisma, McCoy. 



Type, E. pentagonalis. PL 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, Europe, Australia. 



Sub-genus. Phanerotimis, 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. PL X., fig. 19. 



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



H 



