54 LINN^AN GENERA. 



Murex muricatus.— The Muricated Murex. Plate II. 

 fig. 11. Shell strong and rough, with from six to seven 

 ventricose, tuberculated volutions, tapering to a fine point; 

 the tubercles are formed by interrupted, longitudinal ribs, 

 crossed by strong elevated strise, and in some parts are 

 pointed or angulated; apex smooth; aperture oval, termi- 

 nating in a long slender canal ; outer lip sharp and dentated 

 at the edge, margin within crenulated; pillar-lip smooth. 

 Inhabits the British seas, rather a local shell. 



B Base, c aperture, k k, &c. sides, P the beak or rostrum, q canal or 

 gutter. 



The Murices are only found in the ocean. They in general frequent 

 rocky shores, and some of them burrow in the sand. 



Genus 27— TROCHUS. 



Animal a Limax; shell univalve, spiral, more or less 

 conic; aperture somewhat angular or rounded, the upper 

 side transverse and contracted; pillar placed obliquely. 



Linnaeus divides the Trochi into three families : *umbilicated, erect, 

 with pillar perforated ; **imperforate, erect, with the umbihcus closed ; 

 ***tapering, with an inserted pillar, and falling on the side when 

 placed upon the base. 



Trochus papillosus. — The Pimpled Trochus. Plate 

 VIII. fig. 27. Conic, imperforate at the base, spirally 

 granulated, and not marginated at the edges of the volu- 

 tions; body tumid, and spire tapering abruptly to an acute 

 apex; flesh-coloured; one and a half inch long. 



Trochus umbUicatus. — The Umbilicated Trochus. 

 Plate III. fig. 1. Shell conico-convex, flattish, rounded at 

 the top ; apex depressed, volutions five, slightly emarginate, 

 defined by a fine line ; spirally striated, rather whitish, with 

 zigzag lines of purple ; aperture compressed and angulated ; 

 with a large umbilicus which extends to the apex. Found 

 on the Northumberland and Yorkshire coasts. 



c Aperture, u umbilicus. 



The Trochi inhabit the ocean, with the exception of a few land 

 species. They generally frequent pools, which are wet when the tide 

 recedes ; some few of them live in very deep water. 



