APPENDIX TO CHAPTER XI 



175 



usually few ; angle of spire 

 always over 50, usually over 

 90 ; aperture over \ length of 

 shell. 



. Shell conical, pearly under 

 epidermis and within aper- 

 ture, usually brilliantly so ; 

 umbilicus deep and large . 

 . Shell globular or oval ; spire 

 short, body whorl large ; 

 umbilicus rounded, dis- 

 tinct, either free or covered 

 by a callus ; angle of spire 

 90 or more 



/ 3 . 



/ 4 . 



Shell top-shaped to globular ; 

 interior pearly, 8-30 mm. 

 long ; umbilicus when pres- 

 ent not rounded nor cov- 

 ered with a callus . 



Shell minute, nearly disk- 

 shaped, widely umbilicated 

 Anterior margin of aperture notched 



or produced into a canal. 

 a. Shell with canal formed by a de- 

 cided prolongation of anterior 

 end. 



/i. Large, heavy shells, over 100 

 mm. long, pear-shaped ; 

 whorls angulated or nodu- 

 lous . . . . 



/ 2 . Rather thin shells, 20-80 mm. 

 long, ovate to pear-shaped ; 

 whorls rounded and cov- 

 ered with 40-60 small re- 

 volving ridges . . . 



/s. Shells over 20 mm. long, with 

 longitudinal, rib-like undu- 

 lations crossed by revolving 

 lines . 



Trochidw 



Naticidce 



(Ex. Natica) 



Littorinidce 



(Ex. Littorina) 



Adeorbidce 



Fasciolariidce 



(Ex. Fulgur) 



Biiccinidce 



Muricidce 



(Ex. Urosalpinx) 



