94 MUREX. ROCK-SHELL. 



- 16. Murex Chordula. Twine Rock-shell. 



Shell conic, a little tapering to a rather obtuse point, 

 pale chesnut-brown : spires five, rounded and well denned, 

 the first occupying more than half the length, with about 

 fifteen raised rounded wire-like ribs of equal diameter 

 throughout, which continue over the junctions of the volu- 

 tions, and curve in the middle towards the outer-lip ; they 

 are also crossed by very fine spiral striae : aperture narrow 

 oval, ending in a short canal 5 the outer-lip thickened by a 

 rib on the back ; inner-lip a little spread : length not two 

 lines ; breadth the third of its length. 



This delicate species differs from M. rufus, in having 

 fewer volutions, in the ribs not being protuberant in the 

 middle, and in their curvature in the middle of each voUu 

 tion $ it is also never half the size. 



Drifted sand, in Dublin bay. v. m. 



17. Murex linearis. Linear Rock-shelL 



Montagu, pi. 9. f. 4. 



Murex elegans. Donovan, pi. 179. f. 3. 



Shell rugged, taper, glossy, light brown with generally 

 a purple tip : spires seven or eight, with about ten strong 

 ribs, crossed by numerous thread-like raised spiral lines, 

 the summits of which are often purple : aperture oval, 

 ending in a straight short, very open canal ; the outer-lip 

 thickened by a rib, the margin crenate by the incurvations 

 of the spiral lines, and toothed within ; pillar-lip smooth : 

 length a quarter of an inch or more ; breadth about a line* 



Western coasts, and Dublin bay. v. v. 



18. Murex purpureus. Purple Rock-shell. 



Montagu, pi. 9. f. 3. 



Shell very rugged, tapering to a very fine point, dark 

 purple with often white blotches : spires nine or ten, 

 rounded, with about twenty ribs running a little obliquely 

 to the right, and crossed by numerous sharp raised trans- 

 verse ridges, which rise into angles on the ribs, and give 

 the shell a very rough or cancelled appearance : aperture 

 oval, ending in a short straight canal ; the outer-lip thin 

 a wiiite margin,, crenate by the outward striae ; inside 



purple^ 



