698 Modification of the Apex in Gastropod Mollusks. 



Genus VITUL,AR1A Swainson. 

 Vitularia salebrosa King. (Fig. 45. ) 



Apex small, angular, carinated, consisting of one and a-half 

 whorls, rapidly increasing. The first whorl is flat and cap-like, 

 and the second is wide and angular. A carina begins at the initial 

 point of the first whorl and encircles the nuclear whorl and the 

 post-nuclear whorl ; on the latter it is nodular and ribbed. Color 

 of apex white. But a single specimen examined. 



Genus PURPURA Bruguike. 

 Subgenus POLYTROPA Swainson. 

 Purpura lapillus Linne. (Fig. 46.) 



Apex small, rounded, smooth, knob-shaped, consisting of one 

 and a-half whorls very rapidly increasing. The nuclear whorls are 

 smooth and rounded, but the post-nuclear whorls are bicarinated. 

 The carination of the post-nuclear whorls commences very sud- 

 denly after leaving the nucleus. A number of specimens ex- 

 amined. 



Purpura saxicola ostrina Gould. 



The apex in this species is exactly like that of lapillus. Two 

 dozen specimens examined. 



Genus CONCHOLEPAS Lamarck. 

 Coiicliolepas peruvianus Lamarck. (Fig. 47.) 



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

 and a-half whorls, narrowly rounded and white in color. The 

 post-nuclear whorls are strongly ribbed and striate, and the last 

 whorl nearly conceals the nucleus. Two perfect specimens ex- 

 amined. 



Family JANTHINID^. 



Genus JANTHIIVA Lamarck. 

 Jantliina gloliosa Swainson. 



The apex of this species is very small and is buried in the volu- 

 tions of the post-nuclear whorls. There is no line of junction be- 

 tween the nuclear and post-nuclear whorls, and the number of 

 nuclear whorls cannot be counted. All of the whorls are of a 

 delicate purple color. A dorsal view of the apical whorl is like 

 fig. 40, and a lateral view like fig. 39. 

 Janthina communis Lamarck. 



Same as J. globosa. 



