390 



THE WORM-SHELL. 



ON the right hand of the illustration is seen an elongated shell, shown together with 

 the animal. 



This is the GREAT CLUB-SHELL, a species belonging to the typical genus of the family. 

 It is rather a large genus, containing at least one hundred known species, and ranging 

 over the whole world. The largest species are, as is usually the case, to be found within 



PELICAN'S FOOT. Aporrhdis pes-pelicdni. 



LARGE CLUB. Cerithium palustrt. 



the tropics. The shell is considerably elongated, and with many whorls, and the " varices " 

 or marks of growth are partially visible on the exterior. The aperture is decidedly small 

 when compared with the dimensions of the shell, and has a somewhat twisted canal in 

 front. The outer lip is rather wide, and the inner is much thickened. 



One of these shells, the MARSH CERITHIUM (Cerithium palustre), is supposed by some 

 persons to produce the strange sub-aquatic musical sounds that exist in several Eastern 

 lakes. A detailed account of these sounds, together with the reason for this conjecture, 

 may be found in Sir J. E. Tennent's " Natural History of Ceylon." 



The colour of the Great Club- shell is deep chocolate-brown on the exterior, slightly 

 mottled with varying tints, and the interior is brown, but without the chocolate hue. 



IN the family of the Turritellidse, the shell is either tubular or spiral ; the aperture is 

 not waved, notched, or formed into canals ; the foot is very small, the muzzle is short, and 

 the eyes sunk rather deeply into the base of the tentacles. 



THE figure on the left-hand of the accompanying illustration represents a species 

 belonging to the typical genus of this family, the COMMON TURRITELLA. 



In all the Turritellas the shell is long, pointed, and with many whorls ; the aperture is 

 rounded and its edge thin ; the operculum is horny and with many whorls, and with a 

 slightly fringed edge. About fifty species of these shells are known, spread over the whole 

 world, and inhabiting the moderately deep waters of the shores, ranging from a depth oi 

 one to fifty fathoms. They are supposed to be carnivorous. The colour of the Common 

 Turritella is whitish. 



THE curious WORM-SHELL, which derives its name from its long and twisted form, is 

 a very remarkable shell, and, if carefully examined, affords much instruction as to the 



