Modification of the Apex in Gastropod Mollusks. 691 



as in mercatoria and the extra one and a-half whorls are narrowly 

 rounded. The lateral outline makes an obtuse cone. Color as 

 in the preceding species. Three specimens examined. 



Colum1>ella rustica Linn6. 



Apex in all respects like that of mercatoria. Sometimes lighter 

 in color. Four specimens examined. 



Columlbella fuscata Sowerby. (Fig. 42.) 



Apex small, conical, elevated, smooth, consisting of two and a- 

 half regularly increasing whorls, which are spermaceti-like. This 

 apex differs from the preceding in its sharply conical form. 

 About a dozen perfect specimens examined. 



Columbella avara Say. 



The apex of this species is like that of fuscata. A number of 

 specimens examined. 



Family MURICID^. 

 Genus MUREX Linne. 

 For the sake of comparison the following species of this genus 

 are introduced, but have been published in the works cited above. 



Murex: scolopax Dillwyn. (Fig. 43.) 



The nucleus consists of two smooth, glossy, fulvous whorls, 

 of which the second is twice as large as the first ; a carina be- 

 gins at the apex and after traversing the first and second whorls 

 in an oblique direction, finally ends in the suture above the third 

 whorl. The top of the first whorl is flat, the lateral outline of the 

 whorls descends outwardly in a straight slant to the carina, and 

 from the carina to the suture below it slants inward. The carina 

 of the last whorl is much lower nearer the suture than that of the 

 fii'st, giving the two whorls somewhat the appearance of a stumpy 

 smoke-stack of a locomotive. The last nuclear whorl ends with a 

 triangular varix, which is thick, whitish and semitransparent. 



Murex aduncospinosus Beck. (Fig. 44.) 



The nucleus consists of two and a-half blunt, conical, glossy, 

 fulvous, flat sided whorls, which increase regularly from the apex ; 

 the last whorl is margined below by a very fine thread just at the 

 suture ; the lateral outline shows a cone of about three regularly 

 increasing whorls, of which the third is twice as large as the first. 

 There is a rounded varix of considerable size at the end of the 

 last nuclear whorl. 



