HANDBOOK OF SHELLS. 47 



with it are classed the " Tun " (Dolium) and the great 

 "Triton" (Triton tritonis), such as the sea-gods 

 of mythology are represented blowing into by way 

 of trumpet, and which are used by the Polynesian 

 Islanders to this day instead of horns. 



5. The Conidce, whose type, the " Cone-shell " (Fig. 

 n), is at once distinctive and handsome, but which in 

 the living state is covered by a dull yellowish-brown 

 periostracum that has to be carefully removed before 

 the full beauties of the shell are displayed. 



6. The Volutidce, embracing the Volutes and 

 "Boat-shells" (Cymba). 



7. The Cyprceida, or Cowries (Fig. 12), which owe 

 their high polish to the size of the shell- secreting 

 organ (mantle), whose edges meet over the back of 

 the shell, concealing it within its folds. With 

 these is classed the " China-shell " (Ovuluni). 



The second group, or Holostomata, is divided 

 into nineteen families, beginning with 



1. The Naticida, whose type, the genus Natica, Fig< 1 . 1 - 7 . 

 is well known to all shell-collectors through the Vl 

 common Natica monilifera of our coasts. 



2. The Cancellariadiz, in which the shells 

 are cancellated or cross-barred by a double 

 series of lines running, one set with the whorls, 

 and the other across them. 



3. The Pyramidellida, which are high- 

 spired, elongated, and slender shells, with the 

 exception of the genus Stylina, which lives 

 attached to the spines of sea-urchins or buried 



in living star-fishes and corals. p- ^ ^Cytn 



4. The Solaridtfy or "Staircase-shells," ' oriiscus. 

 whose umbilicus is so wide that, as you look down it, the pro- 

 jecting edges of the whorls appear like a winding staircase. It 

 is a very short-spired shell. 



5. The Scalarida, " Wentle-traps " or "Ladder-shells," 

 which may be readily recognised from their white and lustrous 

 appearance and the strong rib-like markings of the periodic 

 mouths that encircle the whorls. 



6. The Cerithiadce, or "Horn-shells," which are very high- 

 spired, and whose columella and anterior canal are produced in 

 the form of an impudent little tail, the effect of which, however, 

 in the genus Aporrhais, or " Spout-shells," is taken away by the 

 expanded and thickened lip. 



