

GASTEROPODA. 



135 



W. Indies, Zanzibar, 



fissure. Operc. with a broad, membranous border. 

 Pacific. 



Modulus, Gray (and nina, Gray) M. tectiun, PL IX., fig. 13. Shell tro- 

 chiform or naticoid ; porcellanous ; columella perforated ; inner lip worn or 

 toothed ; operc. horny, mftey-whirled. Distr., Philippines, W, America. 



Fossarus (Adaus.) Philippi. F. sulcatus, PL IX., fig. 12. Syn., pha- 

 sianema, Wood. Shell perforated ; inner lip thin; operc. not spiral. Distr., 

 Medit. Fossil, 3 sp. Miocene . Brit., Medit. 



Risella, Gray. Lit., melanostoma, PL IX., fig. 14. Shell trochiform, 

 with a flat or concave base ; whirls keeled ; aperture rhombic, dark or varie- 

 gated, operc. pauci-spiral. Distr., N. Zealand. 



SOLARIUM, Lam. Stair-case shell. 



Etym., solarium, a dial. 



Syn., architectoma, Bolten. Philippia, Gray. Helicocryptus, D'Orb? 



Type., S. perspectivum, PL IX., fig. 15. 



Shell orbicular, depressed ; umbilicus wide and deep ; aperture rhombic ; 

 peristome thin ; operculum horny, sub-spiral. 



The spiral edges of the whirls, seen in the umbilicus, have been fancifully 

 compared to a winding stair-case. 



Distr., 25 sp. Tropical seas. Medit., E. Africa, India, China, Japan, 

 Australia, Pacific, W. America. 



Fossil, 56 sp. Eocene . Brit., &c. 26 other sp. (oolites chalk,) are 

 provisionally referred to this genus ; the cretaceous sp. are nacreous (v. 

 trochus). 



Sub-genera. Torinia, Gray. T. cylindracea, operc. conical, 

 multi-spiral, with projecting edges, fig. 82. Living, New Ire- 

 land. Fossil, Eocene. Brit. Paris. 



Omalaxis, Desh. (altered to bifrontia) S. bifrons, discoidal, 

 the last whirl disengaged. 6 sp. Eocene, Paris, Brit. 



? Orbis, Lea. Discoidal, whirls quadrate. Fossil, Eocene, 

 America. 



? PHORUS, Moritf. Carrier-shell. 



Fig. 82.* 



ihoreus, a carrier. 

 Syn., onustus, Humph., Xenophorus, Fischer. 

 Examples, P. conchyliophorus, Born. P. corrugatus, PL X., 

 Shell trochiform, concave beneath ; whirls flat, with foliaceous 

 or stellated margins, to which shells, stones, &c., are usually 

 affixed ; aperture very oblique, not pearly ; outer lip thin, much 

 produced above, receding far beneath. Operc. horny, imbricated, 

 nucleus external (as \i\purpura and paludomus,) with the trans- 

 verse scar seen through it, fig. 83. (Mus. Cuming.) 



* Operculum of S. patulum, Lam. f , from Deshayes. 



fig.l. 



