376 MOLLUSCS. 



of Tiirbinellidw, the shells are compact and very strong, tuberculous or spiny, 

 with short spires, and the anterior canal considerably shorter than in Turbinella. 

 The aperture is armed with a few folds on the middle of the columella, and is closed 

 by a thick and somewhat twisted operculum. The eight known species are dis- 

 tributed over the Red Sea, Philippine Islands, Polynesia, Pacific coast of Central 

 America, and the West Indies. Fulgur and Melongena both include large striking- 

 shells from the United States and West Indies ; and Sycotypus canal icidat its, also 

 from the States, is remarkable for the deeply channelled suture separating the 

 whorls. The egg-capsules are very curious, consisting of a long string of round 

 discs, about the size of a shilling, but somewhat thicker, attached to the cord by 

 one edge. Each capsule contains a number of eggs, and the young eat their way 

 out at a spot opposite the points of attachment. Semifusus colosseus is one of the 

 largest living gastropods, attaining a length of about 14 inches. It is an 

 inhabitant of the Indian Ocean, and also occurs at the Philippine Islands. Another 

 giant is the well-known Fusus proboscidiferus, of which the broadly fusiform shell 

 sometimes attains a length of 2 feet. It is found on the west and north-west coast 

 of Australia, and on account of the peculiar nucleus of the spire has been placed 

 in a separate genus, Meg alatr actus. The egg-capsules form a cylindrical mass 

 marked with a dozen longitudinal equidistant ridges, and divided off into compart- 

 ments, each compartment containing from twenty to thirty young. When they quit 

 the egg-case, they are about an inch in length, and bear no resemblance to the full- 

 grown shell. 



The whelks form the characteristic group of the family Buccinidoe, which 

 also includes a considerable number of other genera, and numerous species. 



The animals usually have a long siphon and a large 

 foot, more or less square in front and somewhat pointed 

 behind ; the head is provided with a pair of tentacles 

 which support the eyes on the outside. The lingual 

 ribbon is well-developed, with three rows of pronged 

 teeth, the central with three to six cusps, the laterals 

 two- or three - pronged. The form of the shells is 

 variable ; some are fusiform, with a distinct anterior 

 canal, others ovate, with the canal reduced to a mere 



ii An • l l • ii l i 



op (a) Buccinum undatum, (b) notch - A11 are provided with a horny operculum, 

 Murex erinaceus. which assumes different forms in the various genera. 



Chrysodomus is essentially a northern or Arctic race, 

 and one of the fusiform types with a distinct siphonal canal. C. antiquus, the largest 

 of the British marine gastropods, was also common in the English Crags. Reversed 

 or sinistral specimens were the commonest form in the Red Crag. G. contrarius, found 

 living on the coast of Spain and Portugal, is a closely allied species. Sipho, Volu- 

 iopsis, and Jumala are other northern fusiform groups, which have a few British 

 representatives. The common whelk (B. undatum) is the typical representative of 

 the genus Buccinum, and is such a familiar object that a description of the shell is 

 needless. We may, however, direct attention to the variations existing in this species, 

 these being due to difference of locality, depth, etc. Specimens from deep water 

 have much thinner shells than shallow-water forms, and those found on some 



ROW OF TEETH FROM THE RADULA 



