»10 



MOLLUSCA. 



THE CASSIS TUBEROSA. 



THE MUREX REGIUS. 



all power of description in the beauty of its colorings. The large Helmet- Shells, of the genus 

 Cassis, are extensively used in the manufacture of cameos. 



Genus BUCCINUM : Buccimim, includes several species, of which the Common Whelk, B. 

 undatum, is the type ; this is extensively caught in dredges in Europe, as it is eaten, and is also 



used as fish-bait. It is ■nell known to bore through the shells 

 of other mollusca, and thus to suck out the vital parts. A 

 curious illustration of this habit is furnished by Mr. Stephen- 

 son, in describing- the erection of the Lio-ht-house on the Bell 

 Rock, off the Southwestern coast of England. On the first 

 landing of the workmen there, the limpets, of a very large 

 size, were common, but were soon picked up for bait. As 

 they disappeared, an eff"ort was made to plant a colony of 

 mussels, fi-om beds at the mouth of the river Eden, of a 

 i% larger size than those which seemed natural to the rock. 

 ^""^ These larger mussels were deemed likely to prove useful to 

 the workmen, and might have been especially so to the light- 

 keepers, the future inhabitants of the rock, to wdiom that 

 mollusk would have afforded a fresh meal as well as a better 

 bait than the limpet ; but the mussels were soon observed 

 to open and die in great numbers. The reason of this was 

 not readily discernible, but at length it was ascertained that 

 the whelk had greatly increased, and proved a successful 

 enemy to the mussel. It was repeatedly observed to perforate a small hole in the shell, and 

 then to suck out the finer parts of the body of the mussel ; the valves of course opened, and 

 the remainder of the mollusk was washed away by the sea. The perforated hole was generally 

 — such is the instinct of these little creatures — in the thinnest part of the shell ; it was per- 

 fectly circular, but widened toward the outer side, and so perfectly smooth and regular as to 

 have all the appearance of the most beautiful work of an expert artist. Several subsequent 

 attempts were made to plant mussels in this place, but they were all destroyed by the preda- 

 ceous whelks. 



Another British species of "Whelk, the £. kqjillus, produces a purple dye, similar to that 

 obtained by the ancients. Mr. W. Cole of Bristol, in 1684, thus described the process adopted 

 in England for obtaining this color : " The shells being harder than most of other kinds, are to 

 be broken with a smart stroke with a hammer, on a plate of iron or firm piece of timber, with 



THE COMMON WHELK. 



