Occasional Papers of the Museum of Zoology 5 



ings in the substance of the shell. Of fifty specimens examined, 

 forty-six showed the nearly microscopic revolving lines, and in 

 some of the young these lines are particularly well marked and 

 beautiful. Two or three juvenile individuals have a narrow dark 

 band above the periphery, not well defined. 



The illustration of G. informis, p. 283 of Tryon's monograph 

 of the Strepomatidae, is a fairly good representation of G. micro- 

 lineata, though in G. informis the whorls are constricted. In 

 general appearance the species would seem to group with G. live- 

 scens Mke. and G. semicarenata Say. The relationship is uncertain, 

 for the revolving lines of this mollusk are also the most striking 

 characteristic of G. lattitans Anth., of the Green River, a branch 

 of which is Rough Creek. As the Gonibases of streams in the Ohio 

 River drainage north of Tennessee tend in each stream to run 

 together it is not unlikely that farther down Rough Creek material 

 will be found which establishes an unmistakable connection between 

 G. lattitans and G. microlineata. This would be in line with a 

 frequent experience of the collector of Pleuroceridae. 



The shells were taken from the undersides of slabs of water- 

 logged timber, the waste of a mill at the Falls. The habitat was 

 sHmy and ill-smelling, an unusual choice of Hving place for members 

 of the genus, which ordinarily are clean living. 



