Modification of the Apex in Gastropod Molhisks. 701 



Doliuni malea Val. Two and a-half white whorls. 



Solium inaculatum Lamarck. Three light horn-colored whorls. 



Dolium olearium Linne. Three whorls. 



Genus PYRCL.A Lamarck. 



Pyrula papyratla Say. (Figs. 51, 52.) 



Apex small, rounded, smooth and shining, white, consisting 

 of one and a-quarter whorls, very rapidly enlarging. The nuclear 

 whorl looks very like a young Helix. The post-nuclear whorls 

 are beautifully reticulated. The dorsal view (fig. 50) shows a 

 very rapidly enlarging volution and the sharp line between nuclear 

 and post-nuelear whorls. Several specimens examined. 



Pyrula ficus Linne. 



This species has an apex like that of papyratia, but with one 

 and a-half whorls. Five specimens examined. 



Family CYPR^ID^. 

 Genus CYPR^A Linne, 

 Cypraea exanthema Linne. 



The apex of this species is of the same tj^pe as fig. 41, excepting 

 that it is a trifle wider. It consists of three and a-half smooth, 

 dark-brown whorls. Four specimens examined (young). 



Cypraea spadicea Swainson. 



In this species the outline of the whorls forms a /"^ shape, verj'^ 

 much spreading at the bottom. There are three and a-half smooth, 

 yellowish-brown whorls. Two specimens examined (young). 



The collection of Cypraea before me numbers over 160 species, 

 yet the two species quoted above are the only ones showing the 

 young shell, which alone shows the character of the apex. From 

 what I can learn from the adult forms of the other species, I 

 should say that all have the same type of apex, though probably 

 differing in the number and relative width of the whorls,. 



Family STROMBID^. 

 Genus STROMBIJS Linne. 

 Strombus gigas Linne. (Fig. 53.) 



Apex small, rounded, smooth, white, consisting of two and a- 

 ha,lf whorls, regularly increasing. The nuclear whorls are smooth, 



Annals K Y. Acad. Sci., IX, Aug., 1897.— 46. 



