68 AN ANNOTATED CATALOGUE 



Mesodon multiUneaius Say. Very common. A form 

 having the spire much elevated occurs along the Iowa river 

 above Coralville, Johnson county. This species prefers 

 the marshy woodland and mud flats adjacent to the water 

 courses where it often occurs in great abundance. A 

 small woodland pool near Des Moines afforded hundreds 

 of living specimens of this species, which had been borne 

 thither a short time previous, during a rain shower, by the 

 torrent water of a small creek. In hibernation this species 

 is gregarious, several dozen often being found together 

 in a decayed stump, or in a tuft of grass. 



Mesodon thyroides Say. Davenport, Muscatine and 

 eastern Iowa : not usually common. In June, 1886, a num- 

 ber were collected at the base of the high sandstone cliffs, 

 at "Wild Cat Bend" of Pine Creek in Muscatine county. 



Mesodon clausus Say. In Iowa generally this species 

 is not common ; except perhaps at Des Moines where it 

 occurs in abundance. In this locality the most favorable 

 time for collecting this species has been found to be on 

 dry summer days, especially during long drought-periods 

 when the collecting of Helices is generally extremely la- 

 borious and barren in its results. The soil in the wood- 

 land at this time becomes very dry even in localities that 

 are usually comparatively moist ; many plants growing 

 in these localities now wither and die ; to the stems and 

 leaves of those plants, which survive through the season 

 are found attached these snails, often so abundantly that 

 fifty or a hundred have been obtained in a short time ; in 

 fact the most profitable collecting of this species experi- 

 enced. During the day the snail forms around the pe- 

 riphery of the shell aperture an epiphragm which also 

 secures the shell to the leaf. The dew at night sufficiently 

 moistens the plant to allow the animal to move from place 

 to place. 



