36 



water breathing: molluscs into several orders and sections, 

 which it will be foreign to the present purpose even to 

 enumerate ; but the first order, including all the marine mol- 

 luscs, is divided into two sections, animals which draw the 

 water to their gills through a syphon or tube, called the 

 Siphonostomata, or syphon-mouthed, and those which have 

 no such syphon, called Holostomata, or entire mouthed. 

 In those which have no syphons, the outer lip of the mouth 

 is rounded and passes uninterruptedly from the body of the 

 shell to the inner lip, where, as in the syphonated molluscs, 

 the front of the mouth is interrupted by a notch, through 

 which the syphon passes, as in the Volute. This notch fre- 

 quently opens into a tube more or loss prolonged, called the 

 canal, as may be seen in the Triton, the greatest develop- 

 ment of the canal being in the Muricidse generally, and 

 most of all in the Murex Hanstellum. In the Strombus, the 

 typical genus of the Strombidae, there is both a canal and a 

 notch, through which the head of the animal passes. In 

 those species of Strombus which have a smooth lip, 

 this notch 1 is very sharply cut. There are six families 

 of syphonated molluscs. The first is that of the 

 Strombidca, which are generally characterized by a great 

 development of the outer lip, but in no recent shell 

 is it so great as in the extinct species of the 

 Genus Rostellaria. The 2nd family is that of the Muricidse, 

 which, as I have already said, are marked by the great 

 development of the canal and also the exuberance of spines 

 and foliations. The 3rd family are the Buccinidae, of 

 which the Buocinum is the typical genus. The species 

 Buccinum undatum is our common Whelk. The beautiful 

 Harp Shells and Olives belong to this family. The 4th are 

 the Conidae, the typical genus of which the Cone is with 

 few exceptions constant to the form, from which it takes 

 its name. The 6th are the Volutes, which, through all the 

 varieties of their form, may be known by the strong spiral 

 fluting on the front of the inner lip. The 6th are the 

 Cyprseads, the typical genus, the Cypraea or Cowrie is per- 



