3344 THE MOLL US KS OR SHELLFISH 



As in the Marginellidce , the columella exhibits a number of oblique folds, but the 

 aperture is rather more deeply notched in front for the passage of the siphon. The 

 form of the shell is variable; in some the spire being very short, and scarcely rising 

 above the last or body whorl; while in others {Zidona} it is drawn out into a conical 

 spire. The apex is sometimes (as in Yetus} enormous, and all intermediate sizes 

 occur until we come to Volutilithes, in which it is quite small. This latter genus 

 a very common Eocene fossil of the London and Paris basins has very feeble 

 columellar plaits, and is now represented by a single species obtained in one hun- 

 dred to one hundred and fifty fathoms off the Cape of Good Hope. The animals of 

 the volutes are large, sometimes incapable of withdrawing entirely within the shell, 

 and mostly without an operculum. The radula usually has only a single row of 

 teeth, but, in a few instances, a lateral on each side is present. The Yetus shells 

 are large, thin, with enormous apertures, having three or four strong, oblique plaits 

 on the columella. They are found on the west coast of Africa, in the Indian and 

 Pacific Oceans, and also off the Philippine islands. Y. proboscidalis is viviparous, 

 and produces four or five young at a time, about an inch long. The flesh of this 

 enormous animal is said to be eaten, after being dried in the sun, by the natives of 

 Senegal. As an example of the genus Valuta, we may mention the handsome West- 

 Indian V. mustca, popularly known as the music shell, from the color markings, 

 which resemble the lines and notes of music. It is one of the few forms provided 

 with a small horny operculum, and on this account has been placed in a distinct 

 genus ( Volutolyria] by some writers. Like the rest of the true volutes, it 

 is oviparous. The allied genus Volutomitra, as the name implies, has affinities 

 both with Voluta and Mitra; the shell and animal being for the most part 

 mitroid, but the tongue resembling that of the volutes. It may therefore be 

 regarded as a link between the two families. Three or four species are known, 

 one from the shores of Greenland,, and two or three from Tasmania and Kerguelen 

 island. The largest member of the Volutidce (Cymbium broderipi], which is 

 found at the Philippine islands, sometimes attains a length of fourteen inches and 

 thirty in circumference. Rather more than a hundred species of this family are 

 known. 



The gorgeously-colored mitre shells (Mitridci) always have been and still 

 remain a favorite group with collectors. Like the Marginellas, they have no oper- 

 culum, and are small in comparison with the volutes, but they equal if not surpass 

 them in the beauty of their color markings and surface sculpture. The columellar 

 lip is always plaited, the hinder plaits being the strongest. A remarkable feature of 

 the genus, at all events in some instances, is the enormous length of the proboscis, 

 which seems to be out of all proportion to the animal. The tongue of the mitras 

 has three rows of teeth, all serrated in some species, but in others with the two 

 laterals simple, and of a somewhat different type. The common Mitra episcopalis, 

 a striking, scarlet-spotted, heavy shell, is abundant in the Philippine islands, and 

 occurs in Ceylon and in Polynesia. The animal is sluggish in its movements, and 

 buries itself in the sand when the tide recedes. The mitras with simple lateral teeth 

 are mostly ornamented with longitudinal ribs or plicae, and constitute the group 

 Turris. Some frequent coral reefs, and others are found, often in considerable 



