MUREX. 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 im 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 
longitudimal 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 isa 
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 striz of mcrement of the Muricidal oper- 
