460 PROCEEDINGS OF THE ACADEMY OF [July, 



folds, all of which evanesce before reaching the aperture, plications 

 invisible in the aperture. 



Dimensions. — Altitude, 62 mm.; length of aperture, 31 mm.; 

 maximum diameter, 20 mm.; spiral angle, 40° on posterior whorls, 

 decreasing to 25° on anterior whorls. 



This species is one of the most abundant and best preserved 

 univalves at Coon Creek. It shows a considerable range in size 

 and external ornamentation. Some of the young individuals exhibit 

 a fine spiral sculpture over the entire length of the shell. The number 

 of columellar plaits is variable. These terminate far within the body 

 whorl, distant from the margin of the aperture, and in many indi- 

 viduals are almost entirely obscured, although they are readily 

 revealed by sectioning the spire. A comparison of this form with 

 two other members of the section of the genus, one from Owl Creek, 

 the type locality of "Drillia ? distans" Conrad and the other from 

 Corsicana, Texas, indicates that the Coon Creek species is interme- 

 diate between those cited. 



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

 Creek, McNairy County, Tennessee. 



Section B. New section. 



Type: Drilluta major sp. nov. 



This section is characterized by a large, much elevated and 

 elaborately sculptured shell. The whorls are abruptly shouldered. 

 The posterior shoulder is marked by spinous regularly spaced varix- 

 like projections. It is proposed for a well-defined group of Drillutce 

 which include, besides the Coon Creek species, a species from Owl 

 Creek and another from Brightseat, Maryland, which has been 

 questionably referred to Fasciolaria* on account of the imperfect 

 character of the material. The description and figures of Voluta 

 magnified Griepenkerl 9 and Voluta (Volutilithes) subsemiplicata 

 (d'Orbigny) G. Mi'iller 10 present generic and sectional relations which 

 suggest this section of Drilluta. 



Drilluta major *p- nov. PI. XXIII, figs. 7 and 8. 



Description. — Shell thick and large, fusoid in outline; whorls closely 

 appressed, seven in number and increasing slowly in size; apex 



8 Gardner, J. A., Md. Geol. Surv., 1916, Cretaceous, Upper, p. 438, pi. xiv, 

 fig. 11. 



9 Griepenkerl, O., 1889, Palaeontologische Abhandl., Berlin, Band IV. Heft 5, 

 p. 94 (396), Taf. viii, fig. 2. 



10 Mliller, G., 1899, Abhandl. d. Kon. Preus. geol. Landesanstalt, neue Folge, 

 Heft 25, p. 123, Taf. xvi, figs. 10-18-21. 



