Gastropoda. 



20 



The remaining families constitute the second sub-order of the 

 IVctinibranchia- the Stenoglossa. In these the mouth is at the 

 end of a protractile proboscis, and the radula has only two or three 

 teeth in each row ; these are, however, strong and often heavily 

 serrated. 



The Fasciolariidae contain two of the largest living Gastropods : 

 Megalatravlus ar nanus, from North and West Australia, and 

 Fasciolaria gigantea, which is found off the coast of South 

 Carolina, and attains at times a length of 2 feet. 



The Mitridae are great favourites with shell-collectors on 

 account of their beautiful colours and varied sculpture. Shells 

 of this group, like the Fasciolariidae, are distinguished by a few 

 plaits or folds on the inner side of the aperture (the columella). 

 They are almost exclusively found in tropical or sub-tropical 



Fig. 20. 



Heteropod (Carinaria lamarcki). 

 a. proboscis ; b. tentacles ; c. shell ; d. gill ; e. foot ; /. sucker. 



regions, the majority being met with either at low- water mark or 

 in comparatively shallow water. 



The Buccinidae also contain a very large and varied 

 assemblage of forms. Among them may be mentioned the 

 Whelks (Buccinum). 



The family of Muricidae, or ' Rock-shells ', contains many very 

 handsome and peculiar forms. They are all carnivorous, feeding 

 chiefly on other Mollusca, boring through the shells of Lamelli- 

 branchia and slowly devouring the inhabitants piecemeal. The 

 shells of Murex produce at intervals ribs, which in some species 

 are ornamented with long spines or foliations. From certain 

 species of Murex (M. brandaris, &c.) found in the Mediterranean 

 was manufactured the celebrated Tyrian dye. 



The Purpuridae are found between tide-marks all over the 

 world. The Goralliophilidae are sedentary, living on or in corals. 

 In Magilus, which in its early spirally coiled stage settles down 

 on a coral {Meandrina), the aperture of the shell grows into an 

 elongate tube, in order to keep pace with the growth of the coral. 



