40 THE NAUTILUS. 



Poly gyra prof unda (Say). PI. V, fig. 12. 



Near Hoge's Bridge, Morris, Ills., 1910. This shell had formed 

 a peristome, then carried the shell forward twelve mm. and formed a 

 second peristome. The shell between the two peristomes is white, 

 has no epidermis, and has a rough appearance. 



Polygyra albolabris (Say). PI. V, fig. 13. 



North Vernon, Jennings Co. Ind., 1903. In one specimen the 

 last two-thirds of the body-whorl has been injured, resulting in a 

 linear furrow running parallel with the suture. Another shell 

 (fig. 13) was injured before forming the peristome which has two 

 projecting points. The umbilicus is partly open. 



Polygyra exoleta (Binn). PI. V, fig. 14. 



Mitchell, Ind., 1901. Peristome malformed, bisinuate. 



Polygyra elevata (Say). PI. V, fig. 15. 



Mitchell, Ind., 1901. This specimen appears to have attained its 

 growth, and apparently had partially formed the peristome, for at 

 the proper place a parietal tooth was formed which is about one-half 

 grown. The last half of the body-whorl was then broken off and a 

 new peristome and parietal tooth were formed. 



Polygyra hirsuta (Say). PI. V, fig. 7. 



Bass Lake, Starke Co., Ind., 1902. 



Aperture malformed exactly as in the specimen of elevata des- 

 cribed above, the last part of the whorl having been broken off after 

 the parietal tooth was half formed, and a new peristome and tooth 

 were developed a fourth of a whorl behind the original aperture. 



Polygyra fraterna (Say). PI. V, fig. 5. 



Brookville, Ind., 1903. 



This shell had formed a peristome and parietal tooth, then carried 

 the shell forward five mm. and formed another peristome and parietal 

 tooth, the last aperture being small. The original parietal tooth 

 remains standing deep within. This shell belongs to the same class 

 of monster described above for P. profunda. It is unlike most 

 abnormal shells which are due to breakages, for here a second period 

 of growth is superposed upon a normally formed and completed 

 shell. 



