2 CYPK.EA. 



G. Gwpensis and C. Adamsoni have been placed by some 

 authors together under the name " Cyprceovulum," on ac- 

 count of a resemblance in their system of dorsal striation, 

 but in all other characters their affinities are widely apart. 

 The beautiful G. Barelayi, differing as it does in shape and 

 appearance from the great unique G. leucodon, is the only 

 species, excepting C. suloidehtata, which, in the thick and 

 deeply undercut teeth, resembles it. C. ovulata is very 

 closely allied to C. oniscus ; yet one has the regular dorsal 

 ribs of the normal Trivia, and the other is quite smooth. 



Neither can the species be well separated according to their 

 general forms, or the degree of thickening of their sides by 

 superdeposited enamel, because, in these respects, the species 

 pass from one to the other by imperceptible gradations, and 

 because widely different forms are found in the same species. 

 Thus, the common short G. cameola, with thickened sides, 

 would, in an arrangement depending on forms or lateral 

 expansion, be placed in a group with C. arenosa, which it 

 greatly resembles, while the cylindrical form of the same 

 species would range with C. testudinaria and C. argus. 



The Messrs. Adams, in their able work on the genera, 

 have not only attempted to arrange the great bulk of the 

 smooth cowries into groups according to shape and thickness, 

 but have applied to these groups (of impossible definition) 

 generic names. This, for the reasons above mentioned, gives 

 rise to some great incongruities. For instance, G. leuco- 

 don is made congeneric with G. feUna and G. teres, but placed 

 in a distinct genus from G. sulcidentata, which is certainly its 

 nearest ally. Again, such unlike shells as G. tigris, C.fusco- 

 dentata, and G. helvola are placed in the same genus, while 

 G. tabescens and G. Caurica are placed in different genera. 



The genera Aricia and Luponia cannot be defined as dis- 

 tinct from Cyprcea. 



The genus Gijprceovuium I do not adopt, because C. Capen- 

 sis, its type, although peculiar in its external striation, is so 

 closely allied to several species not so striated, that it could 

 not be well separated from them, and these again could not 

 be separated from others. 



The genus Trivia might, perhaps, be sufficiently definable 

 to be useful if separated from the tuberculated and some 

 other species, many of which are now generally included in 

 the genus. On account of these it will be better, on the 

 whole, to consider Trivia in the light of a subgenus. 





