692 Modification of the A'pex in Gastropod Mollusks. 



and flatly rounded. All but the first whorl are nodulous, the 

 nodules being placed at the shoulder of the whorls. These nodes 

 become elevated spines on the post-nuclear whorls. The color is 

 whitish, the brown stripes beginning on the post-nuclear whorls. 

 The writer can find no variation in a large number of specimens 

 examined. 



Voluta rupestris Gmelin. (Fig. 23.) 



Apex large, mammiform, dull, consisting of one and a-half 

 whorls, of which the first is very large, mammiform, its apex bent 

 in and buried in the second half of the first whorl, and the 

 second (half of second) is very flat and narrow. The nuclear 

 whoi'ls are smooth and the post-nuclear ribbed. Color yellowish 

 white, the flames not appearing until the post-nuclear whorls are 

 reached. This is a peculiar apex, with no tendency toward vari- 

 ation. 



Genus SCAPHELLA Swainsou. 



ScapUella junonia Hwass. (Fig. 24.) 



Apex of good size, rounded, smooth, consisting of one and a- 

 half whorls, rapidly enlarging. The nuclear whorls are smooth 

 and the post-nuclear whorls, for a short distance, are marked by 

 numerous fine, more or less nodular ribs. The color is a dead 

 white, the peculiar squarrish spots appearing on the last half of the 

 first post-nuclear whorl. The whole apex forms a rounded, dome- 

 shaped outline. Three specimens with perfect apices are before 

 the writer, and all show the same characters. 



Genus WEiL.0 Broderip. 

 Melo Broderipii Gray. 



The apex of this species is almost identical with that of Voluta 

 scapha (see figs. 19-20). It is very lai-ge, rounded, and composed 

 of three and a-half whorls. The elevated spines begin on the last 

 half of the first post-nuclear whorl and gradually grow large and 

 strong. This apex is larger than that of scapha. 



Melo diadeiua Lamarck. 



The apex of this species is identical with that of hroderipii. 



Family MITRIDJE. 

 This family seems to be the hardest from which to obtain per- 

 fect specimens. Out of two dozen species, and OA^er a hundred 

 specimens, not a single perfect apex could be found. 



