136 



ELLOBIIDAE 



CARYCHIUM EXIGUUM (Say) 



In the species Carychiuni exiguum the shell measures little 

 more than one-sixteenth inch (1.7 mm.) in length. It is white 

 in color and shining or waxy in texture. It has two lamellae, 



one large and the other small, 

 which extend upward spirally along 

 the columellar axis inside the shell 

 as an evenly ascending shelf. The 

 large lamella is conspicuous at the 

 aperture. The smaller lamella, less 

 conspicuous than the large one, re- 

 volves below it. 



The shell of Carychium exig- 

 uu7n has 4^ relatively inflated 

 whorls. The obliquely oval aper- 

 ture is approximately one-third of 

 the total length. The peristome is thickened and expanded. The 

 shell surface is almost smooth, but shows faintly the growth lines. 

 The records indicate that this species is more abundantly 

 distributed in the northern than in the southern part of Illinois. 



CARYCHIUM EXILE H. C. Lea 



The waxy white shell of Carychium exile differs from that 

 of Carychium exiguum in being more slender and elongated. 



The smaller aperture of exile oc- 

 cupies a little less than one-third 

 the length of its shell. Carychium 

 exile may be distinguished from 

 Carychium exiguum by the sculp- 

 ture of its shell surface, which is 

 noticeably striated vertically. The 

 shell of exile, which measures close 

 to one-sixteenth inch (1.6 mm.) in 

 length, is also a trifle smaller than 

 that of exiguum. The large upper 

 lamella of the columella extends 

 well into the cavity of the body 

 whorl, almost filling it. It is bent sharply downward. 



Carychium exile is widely distributed over most of Illinois. 



