170 CONTRIBUTIONS 



are more separated from each other. In some specimens 

 the ribs and transverse strise are so obsolete as to present 

 an almost perfectly smooth shell. This species very close 

 ly resembles the figure of M. pumila* (Sowerby.) It dif 

 fers in having a transverse furrow, and in the ribs being 

 much stronger than the transverse striae. 



M. Flemingii^ Plate 6. Fig. 177. 



Description. Shell fusiform, transversely and very mi 

 nutely striate ; substance of the shell thick ; spire ele 

 vated, rounded at the apex ; suture linear ; whorls five, 

 obtusely angular above; mouth contracted, nearly straight ; 

 columella with four folds ; outer lip sharp. 



Length .8, Breadth .4, of an inch. 



Observation. This species approaches very closely in 

 many of its characters to the genus Valuta. The regular 

 folds, however, of the columella place it strictly among 

 the tMitrce. It is a much larger shell than the fusoides 

 has no ribs, and is more attenuate. 



M. Humboldtii4 Plate 6. Fig. 178. 



Description. Shell subfusiform, transversely and very 

 closely striate, canaliculate above ; substance of the shell 

 rather thick ; spire ; suture linear ; whorls , 



* Min. Conch, vol. 5, pi. 430. 



t Named after the author of&quot; A History of British Animals,&quot; &c. 

 | In placing the name of the Baron Humboldt to this species, I use 

 that which is among the most illustrious in geology. 



