700 Modification of the Apex in Gastropod Mollusks. 



Cas§is cameo Stimpson. 

 Cassis flaiumea Linn^.. 

 Cassis rufa Linne. 

 Cassis sulcosa Brug. 

 Cassis testiculus Linn^. 

 Cassis pila Eeeve. 

 Cassis sa1>uroii Lamarck. 

 Cassis vilJex Linn6. 

 Cassis glauca lAmxL 



All of the above species have precisely the same form of nucleus 

 as that of granulosa. A number of specimens examined. 



Genus CASSIDARIA Lamarck. 

 Cassidaria ecliinopliora Liiin6. (Fig. 50.) 



Apex small, rounded, smooth, shining, consisting of one and 

 a-half whorls, rapidly enlarging. There is a distinct, elevated 

 line where the nuclear and post-nuclear whorls join, and the latter 

 are encircled by numerous beaded spiral lines. This is quite a 

 constant nucleus. Color spermaceti-like. Two specimens ex- 

 amined. 



Genus OIVISCIDIA Swainson. 

 Oniscidia cancellata Sowb. 



The apex of this species is like that of the last species, ex- 

 cepting that it is a little longer. A single specimen examined. 



Family DOLIID^. 



Genus DOL.IUM Lamarck. 



The members of this genus have a rounded apex very like that 

 of Cassis (Fig. 49) excepting that the whorls are wider and \Q.ry 

 dark horn-color or chestnut-color. The number of whorls varies 

 somewhat. The nucleus is smooth and polished, and the post- 

 nuclear whorls are encircled by beaded spiral lines. The line 

 of junction between the nuclear and post-nuclear whorls is very 

 sharply drawn. A number of specimens of each species ex- 

 amined. 



Dolium galea Linn^. Three and one-half whorls. 

 Dolium fasciatum Linn^. Three and a-half whorls. 

 Dolium perdix Linne. Three whorls. 



