Modification of the Apex in Gastropod Mollusks. 687 



larger and very differently shaped, being broadly rounded instead 

 of flattened. Six perfect specimens examined, with no variation 

 from the above description. 



Oliva irisaus erythrostoma Lamarck. (Fig. 3.) 



Apex smooth and shining, consisting of three whorls, which 

 regularly increase in size, each whorl being about twice the size of 

 the one preceding ; the first two and a-half whorls are rounded and 

 smooth, and the carina begins on the third and increases in 

 strength as the shell grows ; the suture begins to be ver^- deep 

 after leaving the second whorl and soon becomes channeled ; color 

 like spermaceti. Three perfect specimens examined, showing no 

 variation. 



OliTa araneosa juliettae Duclos. (Fig. 4.) 



Apex smooth, shining, consisting of two and one-half whorls 

 rapidly increasing in size ; the first part of the first whorl is very 

 small and the second part very large, rounded and smooth ; the 

 carina begins on the last part of half of the third whorl, and ver y 

 soon becomes heavily marked ; color and texture as in the pre- 

 ceding species. Two perfect specimens examined, with no vari- 

 ations. 



Oliva duclosi Eeeve. (Fig. 5.) 



Apex rounded, smooth and shining, consisting of two and 

 a-half whorls, regularly increasing in size ; there is no carina on 

 the nuclear whorls, but one commences on the last part of the 

 third whorl, or the first after the apex. The color is 3^ellowish 

 white in the specimens examined. The form of apex is similar 

 to literata. Only two specimens were found perfect enough for 

 examination. 



OliTa TOlutella Lamarck. (Fig. 6.) 



Apex rounded, smooth, shining, much elongated, consisting of 

 two and a-half whorls, regularly but slowly increasing in size 

 the carina does not appear until the first post-nuclear whorl is 

 reached, but the sutures of the nuclear whorls are deeply chan- 

 neled. The color and texture is spermaceti-like. This is the 

 most conical apex of any yet examined. Sixteen perfect speci- 

 mens are before the writer, and there is no variation from the 

 above description. 



OliTa 1)iplicata Sowerby. (Fig. 7.) 



Apex rounded, smooth, shining, knob-shaped, consisting of two 



