CHAPTER XIII: THE OLIVE SHELLS. RICE 

 SHELLS. HARP SHELLS 



Family Olivid/B 



Shell cylindrical or fusiform, spiral, highly coloured, por- 

 celanous, polished; without epidermis; columella, lip, sutures and 

 spire more or less covered with enamel deposits; outer lip simple; 

 aperture long, obliquely notched below; operculum small or 

 wanting; foot large, grooved above, with semi-lunar extension 

 in front; posterior end prolonged into a point; mantle reflected 

 over shell, forming large, tubular siphon in front, and a whip-like 

 prolongation behind, which lies in the spiral, grooved suture; 

 radula present; eyes borne on tentacles, or wanting. A tropical 

 family, including few living genera. 



Genus OLIVA, Brug. 



Shell oblong, smooth, thick, heavily enameled, without epid- 

 ermis, colour laid on in two layers in different patterns simul- 

 taneously by mantle folds; spire short; suture canaliculated; 

 columella plaited ; aperture long, operculum wanting. A tropical 

 genus of about a hundred species, distributed chiefly in Central 

 America, the Philippines, Mauritius and Ceylon. This is one of 

 the genera in which the foot secretes the shell, at least in part. 



It is a trick of some shell dealers to remove with acids the 

 outer surface of an olive shell which exposes a layer with quite 

 different pattern. The shell may now be palmed off on an in- 

 experienced collector as a different species or a freak of nature. 



The Red-mouthed Olive (0. erythrosioma, Lam.) has one 

 dependable character, the deep orange-red aperture, but its 

 exterior varies surprisingly, forming several distinct varieties. 

 The shell is thick, heavy and somewhat swollen, below the pointed 

 spire. The surface generally bears more or less distinct wide 

 revolving bands. The pale creamy ground is sometimes covered 



9T 



