132 CONCHOLOGY. 



when decorticated, look like mother-of-pearl ; others have a 

 splendid metallic lustre. The T. agglutinans possesses the 

 faculty of covering itself with extraneous substances, such 

 as stones, corals, fragments of shells, &c. Of this species 

 there are two kinds, which, though conchologically known 

 only by one name, are famiharly known by two ; the Con- 

 chologist and the Mineralogist ; the former so called from 

 being loaded with shells, and the latter with stones, &c. 

 Sometimes the Conchologist is loaded with corals only, and 

 then is called the Zoologist. 



Shell thick, generally pearly, shaped like a top, spire 

 sometimes depressed, sometimes elevated and pointed at the 

 summit, sharp or carinated at its circumference, umbilicated 

 or not ; aperture depressed, angular or sub-angular, some- 

 times heart-shaped, with edges disunited ; the right sharp ; 

 the columella arched, twisted, and often projecting forward ; 

 operculum horny, thin, with numerous spiral whorls, narrow, 

 and increasing a little from the centre to the circumference. 



Trochus imperialis. Trochus asperatus. 



T. longispina. T. rhodostomus. 



T. Solaris. T. spiriulosus. 



T. Indicus. T. costulatus. 



T. radians. T. inermis. 



T. pileus. T. agglutinans. 



T. calyptrseformis. T. caelatus. 



T. fimbriatus. T. tuber. 



T. breyispina. T. magus. 



T. rotularius. T. merula. 



T. Stella. T. argyrostomus. 



T. stellaris. T. Cookii. 



T. niloticus. T. conuloides. 



T. pyramidalis. T. conulus. 



T. noduliferus. T. jujubinus, 



T, cagrulescens, T. Javanicus. 



T. obeliscus. T. annulatus. 



T. virgatus. T. doliarius. 



