MUEEX. 491 



eye; behind these, on each side the neck, is a longitudinal 

 band composed of minute brown points, and anterior to the 

 operculum two sulphur- coloured patches, one on each side. 

 The head is small, compressed ; mouth a vertical fissure in 

 the centre of the fork between the tentacula, from whence, as 

 in the Canalifera, a retractile proboscis is exserted. The 

 tentacula are short, inflated, subrotund, slightly triangular at 

 the bases, and for the terminal part flat and more slender, 

 blunt or very little clavate at the tips ; they are frosted hya- 

 line, and edged throughout all the margins with hair-like lines 

 of a more intense white, giving them a very elegant appear- 

 ance ; the foot is also bordered in like manner. The mantle 

 forms a branchial fold, which does not float beyond the canal 

 of the shell, and it also lines the slight sinus at the upper 

 angle of the aperture. The eyes are comparatively close toge- 

 ther, rather large, immersed exactly in the centre of gently 

 raised subrotund inflations. The foot in front is scarcely 

 auricled at the external angles, square, with a shallow groove 

 dividing the sole in front from the upper lamina, and forming 

 slight labia ; it is gradually constricted in the middle, tapering 

 to a moderately pointed termination, with a very deep central 

 longitudinal groove in the posterior half of the foot, termi- 

 nating at its centre in a minute deep cavity, which undoubtedly 

 pierces the integuments, and appears to communicate with the 

 interior of the foot at its junction with the body. 



This decided cavity and the very deep scission are in some 

 measure new features ; they are either to act as aquiferous 

 canals, or to allow the posterior half of the foot to fold, and 

 thus assist its doubling at right angles. Though medial 

 grooves in the foot of the Gasteropoda are not unusual, I 

 have never met with one like this. The foot is usually carried 

 in advance of about half the length of the tentacula, but during 

 great exertion is sometimes produced to their tips. There is a 

 distinct margined operculigerous lobe without wings or caudal 

 appendages, on which is fixed a very light horn- coloured, 

 subrotund, corneous operculum at some little distance from 

 the termination of the pedal disk ; this is marked with the 

 usual characteristic striae of increment of the Muricidal oper- 



