GASTROPODS, 
379 
narrow, with three rows of teeth; the central tooth having three principal cusps 
or spines, and other secondary denticles, and the laterals being simple. The horny 
operculum is variable, having either a lateral or terminal nucleus. The shells 
exhibit much diversity of form in the different groups. Murices are carnivorous, 
feeding upon other molluscs, both gastropods and bivalves. In the typical genus 
Mur ex the animal, as it increases in size, produces at intervals beautiful foliations 
or spine-bearing ridges, nearly always three or more on a whorl, which are some¬ 
times continuous up the spire ; the siphonal canal being sometimes remarkably long 
and slender, almost closed and nearly straight. In this group many of the species 
are armed with numerous long spines upon the ridges; M. tenuispina from the 
Indian Ocean, Philippine Islands, and neigh¬ 
bouring localities, being a striking example. In 
the section Chicoreus the shells are strong- with 
three beautifully branched ridges, and the canal 
shorter than in the preceding group ; M. ramosus, 
a large and abundant species from the Red Sea, 
Indian Ocean, Polynesia, etc., and the beautiful 
M. palma - rosce, from the Philippines, being 
examples. The species of Muricantha are like 
Chicoreus in form, but with numerous varices. 
The west coast of Tropical America and West 
Africa produce some of the largest and hand¬ 
somest species. Of all the group, perhaps none 
surpass in beauty of construction some of the 
forms of Pteronotus ; M. lobbeckei, from the China 
Sea, which is of a uniform delicate rose-pink 
tint, and ornamented with elegant fluted frill¬ 
like varices, being pre-eminently beautiful. There 
are. several other groups, containing a number of species of considerable interest, 
which cannot be further referred to in this account. Some mention, however, must 
be made of the dye which can be extracted from the animals of this family. 
Species of Murex and probably of Purpura— a genus referred to subsequently 
—were both employed in ancient times in the manufacture of the Tyrian purple. 
The dye was obtained from a white vein at the upper part of the neck of the 
mollusc. When first extracted, it is of the colour and consistency of cream, 
but subsequently changes, on exposure to light, to the deep purple tint. The 
common British Purpura lapillus affords similar dye. Its scarcity and the 
use of cochineal, and other dyes, render it valueless as a commercial product. 
Murex erinaceus, the only British species, is common on oyster-beds, to which it 
is destructive. All the forms yet referred to have a somewhat roundish or ovate 
operculum, with the nucleus terminal or subterminal, whereas in those which 
follow ( Purpurince ) it is lateral. All the members of the genus Purpura are 
furnished with strong, heavy shells, suitable for protecting the inhabitants from the 
rough usage of the sea upon the rocky shores they mostly inhabit. They range from 
the Arctic to the Antarctic regions, the handsomest species coming from tropical 
seas. The fry of several species are pelagic, and swim at the surface of the water. 
animal of Murex. b, Gill; b', Osphradium, 
or olfactory organ ; p, Purple-gland, 
