28 THE NAUTILUS. 



whorls has a major diameter of 2'7 ram.; one of the variety, with 

 exactly the same number of whorls, measures 4'0 mm., and my 

 largest specimen 5'5 mm. 



HELICES IN ILLINOIS. 



BY W. S. STRODE. 



lu the Spoon river region of central Illinois, Polygyra muttilineata 

 is probably the most numerous of all the Helices. In the heavily 

 wooded districts bordering the banks of the stream, where rotten 

 logs, decaying leaves and vegetation are in the greatest abundance, 

 they attain the largest size. Further back near the blurts they are 

 much smaller, not being more than one-half the size of those found 

 near the river's bank. This difference which is due probably to 

 environment, has given rise to the so-called multilineata major and 

 minor. Not long since while driving across the bottom a mile from 

 the river, I noticed many snails in the wagon track and crawling 

 across the road. Just on my left was a tract of swamp prairie land 

 containing several acres. The previous season this had grown up 

 with tall prairie grass two or three feet in height, but a day or two 

 before it had burned over. Going over to it I found the ground 

 thickly strewn with multilineata which the fire had killed. Wher- 

 ever a bit of grass, log or rail had escaped the fire, live ones could 

 be picked up by the handful. It was the most extensive snailery 

 I had ever seen. Thousands of them dead and alive, but not an 

 albolabris nor &profunda nor a Helix of any kind except ti\e multi- 

 lineata; and in coloration from those that were almost albinos to 

 the rubra with scores of lines, and all were the minor variety. 

 Pyramidula alternate is the next species in relative abundance. 

 Taking both upland and lowland it probably will outrank the r/- 

 tilinenta. Then comes the />/"'''*'''"> which in some localities is quite 

 abundant. P. hirsuta, profunda, mitehelliana and albolabris will 

 rank in the order in which I have placed them. On the overflow 

 land of the Illinois River a snail is rarely to be found. Further back 

 near the foot-hills and on the margins of creeks tributary to this 

 stream, they are quite common and fine. In these localities are to 

 be found a few Polygyra elei'ntn Say, quite rare in the Spoon River 

 region. 



