SUCCINEIDAE 



123 



almost throughout the state. It is apparently more abundant in 

 the northern than in the southern part of Illinois. 



The habitat of this amber snail is more often on a flcodplain 

 of a river valley than in any other location. Of a dozen known 

 localities in different parts of the state, 10 are in floodplain areas 

 where the forest consists of elm, oak, hickory, willow, sycamore 

 and maple. In a few places, Succinea ovalis optima occurs on 

 upland areas in woodlands where there is abundant shade. 



SUCCINEA CONCORDIALIS Gould 



A southern species of Succinea, concordialis is about one-half 

 inch (14 mm.) in height. The color of the shell is a rather 

 deep amber; the apical whorls are somewhat reddish or orange 

 colored. The shell is thin. The 

 body whorl is flattened near the 

 upper part and swollen or sac- 

 like at the lower part. The aper- 

 ture is obliquely ovate, and the 

 columellar region is notably con- 

 cave. This species may be dif- 

 ferentiated from retusa, which 

 it som.ewhat resembles, by the 

 swollen form of the body whorl 

 and by the reddish apex. 



Succinea concordialis is known in Illinois from but one 

 locality. A. A. Hinkley has collected it on the bank of the Little 

 Muddy River near Dubois, Washington County, "north of the 

 R. R. bridge on the west side of the embankment." This species 

 is common in the south, in Louisiana, Alabama and Texas. It is 

 known also from Des Moines, Iowa, where, Pilsbry records, 

 "It lives on the moist earth immediately adjacent to the water's 

 edge, and where found is usually abundant." 



Pictured on this page are two individual variations which 

 occur at Dubois. One is narrow, which is typical, and the other 

 is slightly inflated. 



The length of the vertical line is the height of the specimen 

 represented by the figure at the left. The figure at the right, 

 representing a specimen which is a variation from the typical 

 shell of Succinea concordialis, is proportionately larger than that 

 of the typical shell. 



