39 



MONOGRAPH OF THE GEJNUh. 



SIGARETUS, Lamarck. 



Including Naticina, Gray. 



Genus Sigaretus. — Testa fere tecta, auriformis ovato-sub- 

 orbicularis vel ovato-subconica subumbilicata, plerumque 

 spiraliter incisa vel lirata ; spira brevi, interdum immersa, 

 ultimo magno inflate ; apertura magna labio interne medio 

 et supra plerumque incrassato. — Operculum corneum parvum 

 imguiculatum planatum, — The shell is nearly covered by the 

 lobes of the animal, which is proportionally large. The more 

 typical species are depressed, ovate or orbicular, with very 

 short spire and large body-whorl, with expanded mouth. 

 They present little variation in sculpture, and few of them 

 have colour. In the ' Naticina' group the shells are perpen- 

 dicular and conical. The operculum is supposed to be 

 rudimentary, but a figure is given in Delessert. 



Species. 



Sect. I. — Oblique auriformis. 



1. CONCAVUS, f. 8-11, 18, 19, Lamarck. — Testa globosa, 

 fusco-straminea, intus castanea vel omnino albida, spiraliter 

 valide sulcata spira exertiuscula frequenter lirida, ultimo 

 anfractu latere ventrali ventrieoso, post labium internum 

 excavato ; apertura subpyriformi antice rotunda, labio interno 

 incrassato. — Of a globose form, with the upper part slightly 

 depressed, and the spire conical and depressed ; usual colour 

 brown or straw, chestnut in the interior, but sometimes 

 nearly white. The body whorl is very deep in front, 



