104 UNIVALVES. TROCHUS. 



Of these species there are two distinct varieties: one is 

 called the Conchologist, from its being loaded with frag- 

 ments of shells, and other testaceous substances ; and the 

 other is very properly named the Mineralogist, as its bur- 

 then consists of stones, earths, pebbles, ores, &c. When 

 the former variety is loaded with corals only, it is called 

 the zoologist or coral carrier. They are considered, when 

 heavily laden, as rarities. 



Some species of Trochiare much elongated, and great- 

 ly resemble screw or needle shells. Unlike the rest of 

 the genus, they have an exserted pillar ; and, when placed 

 on their base, they fall on one side. The most promi- 

 nent species are the T. telescopium and T. dolabratus. 



The greater part of the Trochi present a brilliant mo- 

 ther-of-pearl appearance when uncoated; others have 

 only their aperture pearly or silvery; and a few exhibit 

 a bronze-like hue. 



There are several reverse varieties of Trochi: the prin- 

 cipal are — T. perversus, T. undulatus, T. ventricosus, T. 

 annulatus, and T. pusillus; the latter of which is found 

 within larger shells, in the sands of India. 



The T. flumineus is a river species, and theT. horten- 

 sis is an inhabitant of the gardens in warmer climatef*. 

 The T. terrestris is also a land species, and frequents the 

 mountains of Cumberland. 



Amongst the fossil species, there are two with the 

 whirls contrary, viz. T. ferrugineus and T. novus: the 

 former of which is found near Staphusia, converted into 

 iron-ore. Tlie T. Schrceteri is also found fossil in Cam- 

 pania. 



The following are the places which yield specimens of 

 the Trochi: viz. Asia, Africa, America, Friendly Isles, 

 New Zealand, Red Sea, ^ledifcrrancan, the European 

 and British seas, &c. 



