MUREX. 185 



our British species ; for in M. erinaceus the varices are 

 rather irregular, and in M. corallinus they can scarcely be 

 distinguished from the knobs or tubercular swelHngs be- 

 tween them. 



The head of the animal is half-circular and flat. It has 

 two tentacles, thickened at their bases, where the eyes are 

 placed a little way up. The proboscis is rather long, and 

 can be drawn in at pleasure. The foot is proportionately 

 small, oval or squarish, rounded behind, carrying an oper- 

 culum composed of horny layers placed within each other, 

 the nucleus being near the pointed end. 

 J/, erinaceus is of a yellowish-white colour, having a light- 

 brown shell. The shell may be described as having its 

 general outline conical at both the spiral and chan- 

 nelled ends, and rather angular in the middle of the 

 sides. The whorls are deeply ridged, having varices 

 at not quite regular intervals, rows of scaly projections 

 in front, and tubercular swellings between them. 

 When adult, the canal is closed in by the spreading 

 forwards of the inner lip. 

 M. corallinus is small, of a bright scarlet colour, with a 

 brown, ribbed shell ; the varices are not fringed or scal- 

 loped, or even defined at the edges ; they are scarcely 



