GENERA OF SHELLS. 7? 



Columella arcuated, more or less swelling at 

 base. Operculum. 



Many trochi have a brilliant, pearly surface, and sev- 

 eral have longitudinal ribs, which, we believe, are 

 never found in the turbo. 



T. imperialis, longispina, Solaris, Indicus, radians, pileus, 

 calyptraBformis, fimbriatus, brevispina, rotularius, Stella, stel- 

 laris, rhodostomus, spinulosus, costulatus, inermis, agglu- 

 tinans, coelatus, tuber, magus, merula, argyrostomus, Cookii, 

 Niloticus, pyramidalis, noduliferus, coerulescens, obeliscus, 

 virgatus, maculatus, granosus, squarrosus, incrassatus, flam- 

 mulatus, elatus, marmoratus, mauritianus, imbricatus, trise- 

 rialis, crenulatus, asperulus, acutus, lineatus, ziziphinus, 

 conuloides, conulus, jujubinus, Javanicus, annulatus, dola- 

 rius, granulatus, granatum, moniliferus, iris, ornatus, bicin- 

 gulatus, calliferus, umbilicaris, undatus, Pharaonis, sagitti- 

 ferus, carneolus, cinerarius, excavatus, nanus, pyramidatus, 

 erythroleucos. 



MONODONTA. Shell ovate or conical ; aper- 

 ture entire, rounded ; margins, disconnected 

 above; columella arcuated, truncated at base. 

 Operculum. 



Distinguished from trochus chiefly by the more cir- 

 cular form of the mouth : from turbo by the columella 

 being truncated at base and forming the characteristic 

 tooth-like projection in the aperture. 



M.bicolor, pagodus, tectum-persicum,papillosa, coronaria, 

 ^Egyptigca, carchedonius, modulus, tectum, labio, australis, 

 canalifera, viridis, fragaroides, constricta, tricarinata, articu- 

 lata, lugubris, punctulata, canaliculata, seminigra, rosea, 

 lineata. 



TURBO. Shell conoid or subturreted ; out- 



