THE MUREX SHELLS. ROCK - FAMILY MURICIDAE. Shell spiral, fusiform, with anterior canal or notch; whorls thickened by varices or nodules at each rest period of growth; aperture roundish; operculum horny; mantle enclosed, with ruffled border whose extension lines anterior canal; foot broad, simple; eyes present; branchial plumes, two; radula long, slim, with teeth in three series; sexes distinct.
A large family of marine carnivorous mollusks of high or ganisation, which creep and swim, chiefly in warm seas.
The family Muricidx is divided by Tryon into two sub families; I. Muricintu, adorned with varices, having the nucleus of the operculum near the centre; II. Purpurina, with nodules instead of varices, and with the nucleus of the operculum near the margin.
The genus Murex overshadows all the others in size, elabor ateness of decoration, and number of species.
Sub-family MURICINAE Genus MUREX, Linn.
Shell solid, or pear-shaped, with three prominent spiny or branching varices crossing each whorl, and intermediate ones of smaller size. Canal variable in length, partially closed. About two hundred and fifty species, living from low water to fifty fathoms or more, mostly on tropical or sub-tropical shores of both hemispheres, The rock shells are distinguished by the striking ornamen tation of their whorls by spiny processes. Each varix marks the end of a period of growth, when a barricade is built to guard the temporarily closed doorway. The presence of many secondary 27 The Murex Shells. Rock Shells varices is significant: it means comparative starvation for the mollusk, which instinctively strengthens the edge of the shell when threatened with short rations. The most gaily decked murex, therefore, confesses to the greatest struggle for enough to eat. Richness of apparel is the badge of poverty and privation.
Notice the varices on a number of Murex shells. Some are low ridges, scarcely emphasised by tubercles. The majority of species have these knobs prolonged into spines, horns or leaf like expanses, short and stout, or oftener long, slender, simply or intricately branched. The largest varix fringes the outer lip.
Distinct spiral ridges sculpture the spires on every whorl.
The shells are solid, and limy, lined with smooth enamel, never pearly. That part of the outer varix which interferes with growth is eaten off by an acid secretion to make way for the next one.
The colouring of Murex shells is usually rich, the lining flesh pink in many species. The collector of Murex has a long and interesting road to travel, and he has a cabinet of very showy, large, handsome shells for his pains. For some rare species he has had to pay a good price. Some commercial value attaches to Murex shells used by cameo-cutters and makers of fancy shell articles. The flesh of two species is eaten by the peasants on the Adriatic shores.
"The "Tyrian purple" of antiquity was obtained from mol lusks of several species of Murex and Purpura. Press the oper culum of our humble purple, and a dull red fluid is exuded. It comes from anal glands, and is doubtless protective, like the ink of common squids. Not knowing how to get at it, the Tyrians ground the mollusks in mortar-like hollows in the rocks. The fluid was then separated by squeezing the fleshy parts and dis carding the shell fragments. To this was added five or six times its bulk of water, and twenty ounces of soda to each hundred pounds of the mixture. Evaporation from tin or leaden vessels reduced the dye to the desired strength and colour. Wool dyed in this mixture for a few hours was worth $200 per pound, so expensive was the method of obtaining the colour. The secret of this process, lost in ancient times, was rediscovered centuries later, but the cheaper cochineal and chemical dyes have sup planted all others.
28 The Murex Shells. Rock Shells I follow the grouping of species used by Tryon, giving several under each sub-genus, but not attempting to describe all.