THE COMMON WHELK. 195 



FAMILY III. BUCCINIDJ3. 



The Buccinum,* or " Triton's shell," is the type of another family of carnivorous Gasteropoda, 

 in which the shell mouth is notched in front, or with the canal abruptly bent back. It has excellent 

 lingual teeth for boring into shells with, and a long proboscis-like mouth and siphon, so that when 

 burrowing after the living bivalves on which it feeds it can protrude its mouth into their gaping 

 valves, or drill a hole even into the shell itself, if necessary; moreover, its long siphon is 

 thrust upwards above the mud or sand, so that the animal can at the same time breathe freely. 

 It requires only the opportunity to study the form and habits of the animal inhabiting these 

 snail-houses to perceive that nearly all the peculiarities in the form of shells relate to some special 

 function or habit of life of the animals which inhabit them. / 



One of the most important functions to be provided for in Snails is that oy respiration. 

 In univalves, the aperture of the shell is usually found to be characteristic of tpe division to 

 which the animal belongs, the mouth being entire in most of the vegetable feeders,//nd notched, or 

 produced into a canal in the carnivorous families (or Siphonostomata). But this ^canal, or siphon, 

 is respiratory in its office, and must not, therefore, always be taken as a certain and sure indication 

 of the nature of the animal's food. Thus, for example, Scalaria pretiosa has a holostomatous, or 

 perfect aperture to its shell, but is known to be carnivorous in its diet. If we refer to the Dog 

 Whelk (Nassa reticulata) and the common Whelk (Buccinum undatum), we shall see the long 

 incurrent siphon protruding from the canal of the shell and turned upwards. Into this tube the 

 water passes, and enters a vaulted chamber (formed by an inflection of the mantle of the animal), 

 which contains the pectinated, or plume-like gills. After traversing the length of the gills, it returns 

 and escapes through a posterior siphon, generally less developed than the anterior one, but very 

 long in Ovulum volva, and formed into a tube in Typliis. The object of the long siphon in 

 the Whelk is to enable it to respire freely while burrowing in the sand in search of its prey 

 the poor defenceless J/ya, and other bivalves. 



The shell of the Buccinum is few-whorled, the whorls are ventricose, the aperture of the 

 shell is large, the canal very short and bent back on the shell, the operculum is lamellar, and the 

 nucleus is external. The Buccinum is characteristic of the northern seas, extending from low water 

 to 140 fathoms. Twenty living species have been described. (See No. 2 in figure on p. 196.) 



All round the British coasts and on the shores of Ireland the Whelk is dredged for the 

 market, and is used as bait by fishermen. Many tons of them are annually consumed in the streets 

 of the poorer parts of London. 



The exterior of the shell of the Whelk is invested with a thin straw-coloured membrane, or 

 epidermis, whose existence is scarcely recognised. Shells from a quiet soft sea-bed often have a 

 coat like brown velvet. Many exotic Tritons are remarkable for their rough cuticle. All the 

 Whelk tribe have horny opercula, and the pattern is often characteristic of the genus ; the operculum 

 is never spiral. Gregarious animals, such as the Whelk and Periwinkle, exhibit malformations more 

 frequently than do others ; thus we have Whelks with double opercula, others with shells repaired 

 after injury or curiously contorted. A large percentage in particular localities are met with having 

 the shell reversed. 



The nidamental capsules of Buccinum are aggregated in roundish masses, and often attached to 

 other shells, which, when thrown ashore and drifted by the wind, resemble horny corallines in 

 appearance. Each capsule contains five or six young, which, when hatched, have each a tiny, stumpy, 

 inflated spiral shell, very unlike the adult, of which it becomes, in course of growth, the apex. 



The genus Pseudoliva^ has a thick globular shell, with a deep spiral furrow near the front 

 of the body whorl, and forms, like Monoceros, a small tooth in the outer lip ; the spire of the shell 

 is very short and the suture channelled ; the inner lip is thickened so as to form a callosity ; the 

 mouth of the shell is notched in front. Six species are named from South Africa. 



The genus Halia\ was for many years a great pu/zle to naturalists. It was only known 

 by the existence of one or two shells in collections, and its habitat was lost. In general form 



Buccina, a trumpet. + From pscudos, falsehood ; and olira, from its resemblance in form to Oliva. 



i From hallos, of or belonging to the sea. 



