MUREX. 489 
with all disinterested naturalists, stamp it as a true member 
of the genus Murex. The animal is lively, active, not at all 
shy, and marches with rapidity; it inhabits in great abun- 
dance the littoral and laminarian zones. It must be regarded 
as the type of the British species of this section; it has the 
most intimate and congeneric alliances with the animals of 
the third and fourth sections. 
M. rncrassatus, Miller. 
Buccinum macula, Montagu. 
Nassa incrassata, Auct. et Brit. Moll. ii. p. 391, pl. 108. f. 3, 4; 
(animal) pl. L.L. f. 1. 
Animal spiral, of a pale dirty-yellow throughout, marked 
irregularly on all its organs with small dark lead-coloured or 
brown dots, lines, or blotches. The branchial fold of the 
mantle extends far beyond the short canal, and though cloven, 
forms apparently an entire cylindrical tube, which is con- 
stantly in motion and used as a tentacular organ. The head 
is pale red, with a vertical fissure, from which a long probos- 
cidal trunk issues. The tentacula are not long, but thickened 
from their bases to half the length, at which point the eyes 
are fixed at the internal angles; from whence they taper 
to slender conical points. The foot is truncate anteriorly, 
indented in the centre in front, and curving right and left into 
poimted auricles; when extended it is longer than the shell, 
and tapers posteriorly to a flat, bevelled, emarginate terminus, 
with scarcely a trace of caudal filaments; the operculum is 
corneous, of suboval shape, and shows the subunguiculated 
strie of increment. There are two semilunar branchial 
leaves, one much larger than the other, with dark brown 
transverse vessels, connected with the mantle and neck in 
the usual manner; the heart is a pale, minute, subcircular 
inflation, situate immediately behind the branchize. The 
male has on the right side the ordinary spatulate organe 
générateur, and the testis, which is paler than the ovarium, 
is substituted for that organ; in the female the ovarium is 
large, of a deep maroon-red, mixed up with the pale brown 
liver, and fills the three terminal volutions, 
