A MONOGRAPH OF THE GENUS 

 TURBO. 



Testa ovata, vel orbicularis, vel conica, interdum, umbili- 

 cata, intus margaritacea. Operculum semper testaceumj 

 diversiforme, plerumque crassum. 



Shell ovate, orbicular, or conical, sometimes umbilicated, 

 pearly within. Operculum always shelly, varying in form, 

 generally thick. 



The genus Turbo comprises all the species included by 

 H. and A. Adams under the sub-families Turbinince and 

 Astraliince, embracing Senectus, Sarmaticus^, Lunella, 

 Modelia, Prisogaster, Callopoma, Ninella, Colloma, 

 Astralium, Stella, Guilfordia, UvaniUa, Pachypoma, 

 Lithopoma, Pomaulax, GooJcia and Bolma. It may be 

 useful to retain these names to indicate the different sections 

 of the genus, but the attempt to separate these sections as 

 distinct genera can only be attended with insurmountable 

 difficulties and anomalies. For instance, looking over the 

 list in Adams' ' Genera of Recent Mollusca ' of species of the 

 genus Turbo, and of Senecttis, I find no constant character 

 by which they may be distinguished ; in the latter some of 

 the species are umbilicated, but not all ; all the species are 

 spirally ribbed or grooved, but T. cornutus, which is classed 

 as a Turbo, is also ribbed, and the young of T. cornutiLS, 

 which Reeve has called T. japonicus, is classed as Senectus. 

 Again, some of the species of Astralium, Stella, Uvanilla, 

 Pachypoma, &c., are interchangeable. For instance, I take 

 T. rhodostoma and T. columellaris for one and the same 

 species {T. hcematragus, Menke), but in Adams they are 

 placed in different genera. It might be thought desirable to 

 confine the genus Turbo to the ovate and turbinated species, 



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