402 Proci'C(iiii(/s of the Ohio State .Icddcniv of Science. 



The shell is characterized by its small size and rapidly 

 enlarging whorls. 



Horizon and locality. — Maxville limestone. 

 Upper zone: Below Thompson Residence, White Cottage. 

 Undetermined zone: Middle of Cut Xo. 6, Mt. Perry-Fiilton- 



ham. 



NATICOPSIS ZICZAC-Whitfield. 



18S2, XafiiOpsis cic::ac. Whitfield, Ann. X. Y. Acad. Sci., Vol. II, p. 223. 



Maxville limestone : Xewtonville, Oliio. 

 1891. Xaticopsis ziczac- Whitfield, Ann. X. Y. Acad. Sci., Vol. V, p. 

 590, pi. 14, figs. 15, IG. 

 Maxville limestone : Xewtonville, Ohio. 

 1895. Naticopsis ziczac. Whitfield, Geol. Surv. Ohio, Vol. VII, p. 477, 

 pi. 10, figs. 15, IG. 

 Maxville limestone: Maxville, Ohio. 

 1909. Naticopsis ziczac. Grabau and Shimer, X. .A. Index Foss., p. G73, 

 fig. 933. 

 Maxville: Ohio. 



Description. — Shell less than meditnn size with depressed 

 spire. \\'horls ventricose. abotit two and a half in number, 

 rapidly increase in size. A])erture large, equal to about half the 

 size of the whole shell, roimded. Sutiu'e i^rominent, subquadrate 



Fig. 27. — A'aticopsis ziczac. 



a and b. — Xatnral size and enlarged views of an individual. (After 

 Whitfield.) 



in cross section. Stirface of the whorls of the spire crossed 

 bv transverse stri?e, which are bent backward. Surface of the 

 body whorl also ornamented with transverse striae which bend 

 backward in the sutural third of the whorl, then bv acute bends 



