114 MANUAL OF THE MOLLUSCA. 



Distr., 1 sp. Sicily, adhering to corals. Closely allied to purpura 

 madreporarum, Sby. Chinese Sea. 



RICINULA, Lam. 



Etym., dimunitive of ricinus, the (fruit of the) castor-oil plant. 

 Ex., R. arachnoides. PL VI., fig. 9 (=murex ricinus L.). 

 Shell t thick, tubereulated. or spiny ; aperture contracted by callous pro- 

 jections on the lips. Operc. as in purpura. 



Distr. 25 sp. India, China, Philippines, Australia, Pacific. 

 Fossil, 3 sp. Miocene . France. 



PLANAXIS, Lam. 



Type, P. sulcata. PI. VI., fig. 6. Syn., quoyia and leucostoma. 

 Shell, turbinated ; aperture notched in front ; inner lip callous, channel- 

 led behind ; operculum subspiral (quoyia) or semi-ovate. PI. VI., fig. 7. 

 Distr., 11 sp. W. Indies, Red Sea, Bourbon, India, Pacific, and Peru. 

 Fossil, miocene ? 



Small coast shells, resembling periwinkles, with which Lamarck placed 

 them. 



MAGILUS, Montf., 1810. 



Syn., campulote, Guettard, 1759. Leptoconchus, Riippell. 



Type, M. antiquus. PI. V., figs. 19, 20. 



Shell, when young, spiral, thin ; aperture channelled in front ; adult, 

 prolonged into an irregular tube, solid behind ; operculum lamellar. 



Distr., 1 sp. ? Red Sea. Mauritius. H 



The magilus lives fixed amongst corals, and grows upwards with the 

 growth of the zoophytes in which it becomes immersed ; it fills the cavity of 

 its tube with solid shell, as it advances. 



CASSIS, Lam. Helmet-shell. 



Syn., bezoardica, Schum. Levenia, Gray. Cyprsecassis, Stutch. 



Type, C. flammea. PL VI., fig. 14. 



Shell, ventricose, with irregular varices ; spire, short ; aperture lo 

 outer lip reflected, denticulated ; inner lip spread over the body-whirl ; ca 

 sharply recurved. Operculum small, elongated ; nucleus in the middle of the 

 straight inner edge. 



Distr., 34 sp. Tropical seas; in shallow water. W. Indies, Medit., 

 Africa, China, Japan, Australia, New Zealand, Pacific, Mexico. 



Fossil, 36 sp. Eocene . Chile, France. 



The queen. conch (C. madagascariensis) and other large species, are used 

 in the manufacture of shell cameos, p. 46. The periodic mouths (varices] 

 which are very prominent, are not absorbed internally as the animal grows. 

 ONISCIA, Sowerby. 



Etym., oniscus, a wood louse. Syn,, morum, Bolten. 







