458 PROCEEDINGS OF THE ACADEMY OF [July, 



summit of costse unmarked by lirse; posterior fasciole indicated by the 

 weakening of the axial sculpture; sutures inconspicuous, aperture 

 lanceolate, produced anteriorly into a long canal; outer lip simple; 

 inner lip callous and parietal wall glazed, callus concentrated just 

 below the posterior commissure of the aperture; columella marked 

 by three well-defined but feeble folds terminating within the aperture; 

 posterior fasciole indicated by abrupt constriction of incrementals. 



Dimensions. — Altitude, 35 mm.; maximum diameter, 13 mm.; 

 spiral angle, 59° 20'. 



This very simple, primitive Volute is represented in the present 

 Coon Creek collection by a single individual. The folds of this form 

 terminate so far within the aperture that it is necessary to section the 

 spire in order to observe the columellar plaits. 



Occurrence. — Ripley Formation: Dave Weeks Place, on Coon 

 Creek, McNairy County, Tennessee: 



Genus DRILLUTA gen. nov. 



Etymology: A contraction of .the generic terms Drillia and 

 Voluta. 



Type: DriUuta communis sp. nov. 



Shell strong and fusiform; spire elevated; whorls numerous, 

 increasing slowly in diameter; protoconch very small and smooth; 

 sculpture dominantly axial, the costse interrupted in front of the 

 sutural line by a well-defined but rather narrow fasciole; aperttire 

 lenticular, produced anteriorly into a long, gently recurved canal; 

 outer lip broadly arcuate, simple within; inner lip calloused; colu- 

 mella bearing one well-defined oblique fold, frequently with one or 

 two minor folds behind it, all of which evanesce before reaching the 

 aperture. 



This genus includes a well-defined and widely distributed group 

 of the Volutidse, some of which are undescribed and some that have 

 been described have been variously assigned to such genera as 

 Drillia, Voluta, Fasciolaria and Fusus. DriUuta may be readily 

 separated from Drillia by the absence of a posterior siphonal notch 

 and further by the presence of columellar plaits on the Volute. The 

 typical Voluta has a lower spire and numerous transverse folds. 

 Fasciolaria has a more inflated body whorl and is not characterized 

 by a well-defined posterior fasciole as is the case with DriUuta. 

 Fusus on account of its smooth columella cannot be confused with 

 DriUuta. There are two well-defined groups among the Drillutce, 

 so it seems advisable to separate this group into two sections. 



