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CHAPTER II. 

 THE GASTEROPODA. 



'' Shell-fish "Uses of the Shell The Kinds of Shells Economical Uses of the Mollusca in the Earliest Period and in the 

 Present Day Form and Growth of Shells Parts of a Shell Order I. PROSOBRANCHIATA : (a) 

 SIPHONOSTOMATA Siphonated Gasteropoda Family I. STROMBID.E, " Wing-shells "2. MURICID.E Murex, the 

 Source of the Celebrated " Tyrian Purple " Dye " Mitre-shells " Fusus, the " Red Whelk " Whelks used for Food 

 Hemifusus, one of the Largest of Living Shells 3. BUCCINIDJ3 Buccinum, "Triton's Shells "The "Dog Whelk," 

 Nassa Purpura Its Dye How it Tackles its Prey Magilus Boring in Coral The Harp-shells The Olives 4. 

 CASSIDID.E Cassis "Cameo-shells" Triton Use of the Shell as a Trumpet Growth of Sea Snails 5. CONID^E The 

 " Cones " Their Beaiity and Commercial Value Conus Gloria-maris Terebra, the " Augur-shell " 6. VOLUTION 

 Rarity of the Volutes 7. The CYPR.EHXE Cowries Richness of their Colour and their Value Past and Present 

 Prices of Specimens of Rare Shells The Money Cowry Cuttle-fishing with Cowry Bait Shells as Articles of 

 Ornament in Dress Ovulutn. 



CLASS II. GASTEROPODA. 

 INTRODUCTION. 



AMONG the various natural objects which the ingenuity of man in all ages has converted into articles 

 of use or ornament, both in savage and civilised life, none have attracted a greater amount of 

 attention, or have been more in request, than the shells of Mollusca, especially sea-shells. Their bright 

 colours and diversity of form are amongst their chief charms to the uninitiated ; whilst to the student 

 of natural history they offer ample materials for scientific research. 



The shell in the Mollusc may be regarded as a hardened, or calcined, portion of the mantle, 

 specially provided (like the enclosing ribs of the vertebrata) to afford protection to the breathing 

 organs and heart. Indeed, when reduced to a mere rudiment, as in slugs, such as Limax and 

 Testacella, or in the Marine Snail, Carinaria, <tc., it forms only a hollow cone or plate protecting these 

 organs. This structure (which has sometimes been called a pneumo*-skeleton) is so characteristic of 

 the Mollusca as to have obtained for them the title of Testacea,^ and the common name of "shell-fish " 

 very well expresses the leading feature in the group. Nevertheless, in several families, the shell is 

 either wanting altogether, or is internal, or so rudimentary that it would never be popularly recognised 

 as a shell. When fully developed, the shell of the Mollusc subserves to protect the soft parts of the 

 animal from injury, and the animal itself from the attacks of enemies ; and in some of the Gasteropoda 

 from those variations of temperature and moisture to which the terrestial species are peculiarly exposed. 



Shells are often called the " habitations " of fishes, or of marine animals, or Snails. Every one 

 has seen the device of a Snail, with the motto, " always at home," on juvenile letters. The quarrymen 

 of the Cotswold Hills go so far as to call some fossil shells snail-houses, the same epithet which they 

 apply to the empty shells of the common Garden Snail. The term is not quite correct, for they are 

 more properly skeletons, and we do not " inhabit " our bones, though Byron calls the skull a 

 " tenement," and " the palace of the soul." Nevertheless, the expression is sufficiently indicative of 

 the sense in which it is popularly used, and may pass muster without any further challenge on our 

 part. 



One fine summer afternoon we visited the fish-house of the Zoological Gardens, and paused to 

 watch the manoeuvres of a Hermit Crab housed in a whelk-shell. Just then a lady of distinguished 

 appearance called the attention of her friends to the same truculent animal, and expressed her lively 

 satisfaction at having become acquainted with "the creatures which made that kind of shell." We 

 hope before long that our readers will attain to a better acquaintance with the original fabricator of 

 that common object of the shore, and will know how the forms and patterns of shells are suited to 

 the wants and walfare of their proper owners. 



It may be seen at a glance that many shells are bivalves, \ like the Oyster and Cockle, while a few 

 called "Chitons" are multivalve; but the great majority are single-valved, or univalves, and 

 sometimes tent-shaped, like Patella, or tubular, as in Aspergillum and Dentalium, Vermetiis, and 



* From pneuma, the breath. f From testa, a shell. 



J Two-valved. Many-valved. 



