﻿No. 27. TROCIIUS. 

 Top Shell. Inhabitant a Slug. 



Shell univalve, spiral and subconic, aperture somewhat angular or rounded, 

 upper side transverse and contracted, pillar plaeed obliquely. 



The leading characteristic of the Trochus is the conical shape of its species, 

 the base being broad, and the whorls gradually tapering towards the apex. 

 This form prevails, with very few exceptions, throughout the genus. Some, 

 however, have so strong a resemblance to the Turbo, that frequent mistakes 

 have been made in their classification. A few species of this genus have 

 their surfaces smooth; but the greater number are covered with knobs, spines, 

 tuberculations, or undulations; of which, the Trochus Solaris and the T. Im- 

 pcrialis are striking examples. The former has its margin beset with long 

 spines, placed at regular distances, and, when the shell is perfect, resembling 

 the rays of the sun, as represented in carved work. Many, when uncoated, 

 present a brilliant mother-of-pearl appearance; others have only a pearly ap- 

 erture; and a kw exhibit a bronze-like hue. The aperture to the shell, in 

 this, as well as in many other genera of univalves, is closed by a stony or 

 horn-like operculum, affixed to the animal. 



Most kinds are marine, and some few are found on land, in moist places. 

 The generality of them reside in deep water; others, in shallows that are 

 left nearly dry at the reflux of the tide. The species are very numerous, and 

 several kinds are common to the British shores. The Trochus Conchylio- 

 phorus possesses the remarkable faculty of attaching stones, and frequently 

 shells or fragments of shells, to his testaceous covering, during his period of 

 formation. Mawe says it is highly valued for its rarity and beauty. 



DIVISION I. Shell umbilicated, erect. 

 Family 1st. 



Scientific name. Locality. Scientific name. Locality. 



Niloticus, I. Ocean, China, S. Seas. Concavus, Coroman., N. Zealand. 



Conus, E. Indies, New Guinea. Vernalis, East Indies. 



Spinosus, New Zealand. Conspersus, East Indian Ocean. 



Jujubinus, Mauritius, W. Indies. Ochroleuchus, do. 



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