ELLOBIIDAE 



135 



Family ELLOBIIDAE 



The family Ellobiidae belongs to the suborder Basomma- 

 tophora of the order Pulmonata. Most of the members of this 

 family are classed as marine shells. A few species, like the 

 carychiums, common in Illinois, live far removed from the sea, 

 under forest debris near water or in other moist places. 



In snails of the family Ellobiidae, the shell is somewhat 

 elongated, the spire long or short and the whorls flatly rounded. 

 In most species the elongated aperture usually has one or more 

 folds on the columella, and frequently it also has folds on the 

 outer lip. Figures on the next page show Carychium shells 

 broken to illustrate the position of lamellae within the shells. 



Genus CARYCHIUM MiJller 



In the genus Carychium, which contains the only species of 

 the family Ellobiidae present in Illinois, the white, almost trans- 

 lucent animal has on the head a protuber- 

 ance somewhat resembling a snout. The 

 eyes are located on the head at the base of 

 and behind the cylindrical tentacles. The 

 broad foot is blunt before and rounded be- 

 hind. It is unequally divided into a short 

 fore part and a longer hind part. The base 

 of the foot may be seen by inducing the 

 animal to crawl on a pane of glass. The 

 under view of the animal is shown in the 

 small figure. The large figure pictures an 

 animal and shell of the species Carychium 

 exiguum. 



The tentacles in animals of this genus, 

 as in other animals of this suborder, are con- 

 tractile but not invertible as in the true land 

 snails of the suborder Stylommatophora. 



Key to Species 



Surface of shell almost smooth, showing only growth lines 



exiguum, p. 136 



Surface of shell with vertical striations, as well as growth lines. . 



exile, p. 136 



