152 PHYLOGENY OF FUSUS AND ITS ALLIES. 



removed from Fusiis. The plaited columella is a distinctive feature, 

 but one which might be readily acquired in a strongly accelerated 

 genus. The origin of such plaits has been discussed at length by 

 Dall.* 



Cosmolithes shows a modification of the protoconch which is de- 

 pressed and more of the nature of the early whorls in Clavilithes. It 

 probably was derived independently from Fusus. It is unknown 

 outside of the French Eocene provinces. 



* Tertiary Fauna Florida, vol. Ill, p. 58. 



