92 HAPLOTREMATIDAE 



HAPLOTREMA CONCAVUM (Say) 



No other land snail in Illinois can be confused with the 

 carnivorous Haplotrema concavum, which might be called the 

 tiger of the molluscan world. The shell is about three-fourths 



inch (16-22 mm.) in diameter. 

 The spire is flattened, and the 5 

 whorls are coiled almost in the 

 same plane. The expanded and 

 shallow umbilicus shows all of 

 the whorls clear to the apex. 

 The aperture is almost round 

 or a trifle elliptical, and the lip in most mature specimens is 

 slightly thickened and turned back or reflected at the base near 

 the umbilicus. The top of the aperture is peculiarly flattened 

 and bent downward. When the snail is young, the greenish- 

 white shell is almost transparent. 



Haplotrema concavum is a forest snail found throughout 

 Illinois in river valleys which are w^ell wooded with oak, elm, 

 hickory, basswood, walnut and pine. It is a rather solitary snail, 

 and few individuals are found together, possibly because of its 

 carnivorous habits. It lives under forest debris, old logs, leaves 

 or any other material which afifords concealment and shelter 

 from the sun's rays. It is most abundant in moist woods and is 

 common on floodplains of river valleys. 



This species is found as far north as Quebec, Canada, and 

 as far south as Arkansas. 



A size variation is to be noted in this snail; those specimens 

 from the northern part of Illinois are smaller than those from 

 the southern part. The largest specimen collected from Jo 

 Daviess County measures but five-eighths inch (16 mm.) in 

 diameter, while specimens from Pope County, on the Ohio River, 

 measure seven-eighths inch (22 mm.). The larger size of the 

 southern specimens may be a result of their habitat, which is 

 on limestone bluffs where material for the making of shells is 

 plentiful. 



This snail has suffered from the work of the taxonomist, and 

 its name has been changed several times. It has been placed in 

 the following genera: Macrocyclis, Selenites, Circinaria and 

 Haplotrema. In earlier works it will be found under one of 

 the first three of these names. 



