592 PALAEONTOLOGY OF ILLINOIS. 



Genus KATICOPSIS, McCoy. 

 NATICOPSIS VENTRICOSUS, !N". and P., sp. 



PI. 28, Fig. 13. 



Natica ventrica, 2fOKWOOD and PRATTEN, 1855. Jour. Academy Natural Sci., Philad., p. 76, PI. IX, 



Fig. 10, a, b. 

 Naticapsis (Nerita) Pricei, SHUJIARD, 1858. Transact. St. Louis Acad. Sci., Vol. I, p. 202. 



SHELL ovate, oblique, longer than wide ; spire very much 

 depressed, obtusely rounded at apex; volutions two and a 

 half or three, convex, the last one very large, regularly 

 and rather strongly ventricose in young specimens, but as 

 the shell advances in age its upper portion becomes gradu- 

 ally flattened and sometimes strongly channeled toward 

 the aperture, and at the same time it becomes more or less 

 shouldered just beneath the suture; below the flattened 

 portion it is still evenly rounded to the base ; suture indis- 

 tinct at the apex, but gradually becoming more deeply im r 

 pressed as it approaches the aperture; aperture large, ro- 

 tundato-quadrate, its length usually a little greater than 

 the width, very oblique to the axis of the shell, contracted 

 below near the columella ; lips sharp, strengthened above 

 at its junction with the columella by the callosity of the 

 latter; columellar lip thick, concave, callous, smooth; sur- 

 face marked with numerous very fine lines of growth, and 

 on the upper part of the volutions with rather strong plici- 

 strise, which curve obliquely forward to the suture. In 

 some specimens the original coloring matter is still pre- 

 served, and the fossil presents a delicate vermilion hue. 



Spiral angle from 120 to 130 degs ; length from apex to 

 base of an average specimen, 0.85 inch ; greatest width, 

 0.82 inch; liight of aperture, 0,50 inch; width of same, 

 0.45 inch. 



The foregoing is Dr. SHUMARD'S original description of JV. Price i, the 

 type of which one of us has had an opportunity to examine carefully, 

 and we now have before us an accurate tracing of it from a good draw- 

 ing by Mr. ULFERS. It agrees so closely in almost every respect with 

 the form we have figured that we can scarcely entertain a doubt of 



