340 G. II. Girty — Growth Stages in JVaticopsis altonensis. 



entire height is comprised in the body whorl. The sculpture 

 consists of fine incremental lines which, near the suture, are 

 somewhat stronger and fasciculated. 



This form at once suggests JVaticopsis sicsac, from about 

 the same horizon in Ohio, but the suggestion is at once 

 quenched by the fact that the zigzag markings in the present 

 instance are clearly due to coloration and in the Ohio shell as 

 clearly due to sculpture. In addition to this very important 

 distinction, JVaticopsis ziczac has a much higher spire. Aside 

 from one or two forms which have been described but not 

 figured, this species is most likely, from intrinsic characters as 

 well as from its geologic position, to be identical with JVaticop- 

 sis littonana var. genevievensis. itself known only from 

 description unaccompanied by figures. Now the species litton- 

 ana is not a JVaticopsis and has never been referred to that 

 genus save in this instance, so it seems probable that Meek 

 really intended to write carleyana, which is a JVaticopsis and 

 was described at the same time as Sphairodoma littonana and 

 from the same fauna. On this interpretation Meek's species 

 may possibly prove to be the same as the one under consider- 

 ation, though it is much larger. The two figures of JVaticop- 

 sis carleyana given by Whitfield, though representing the 

 same shell, are as differently shaped as if they were two dis- 

 tinct species. My specimen is quite similar to the one figure 

 and quite unlike the other. Compared with specimens from 

 Indiana which represent typical JV. carleyana, my form has a 

 lower spire and lacks the regular costse or plications below the 

 suture, though at the same time showing the growth lines more 

 definitely. It is also much larger while composed of the same 

 number of volutions. Because of the coloration, which can 

 not, of course, be used as a specific character, it is proposed to 

 call this form JVaticopsis picta. 



Description of Plate I. 



Naticopsis altonensis McChesney (p. 338). 



Figs, 1, 2, 3, 4. Side views of four specimens showing changes in shape 

 and sculpture to maturity. Figures 1 and 2 are enlarged to three diameters. 



Figs. 5, 6, 7, 8. The same specimens, seen from above. Figures 5 and 6 

 are enlarged similarly to figs. 1 and 2. All four specimens are from the 

 Pennsylvanian of Henry, Garland Co., Mo. 



Naticopsis picta n. sp. (p. 340). 



Figs. 9, 10. 11. Three views of a specimen showing well-preserved color 

 markings. Figure 9 is enlarged to two diameters. The specimen is from 

 the Chester group near Tobinsport, Perry Co. , Indiana. 



