396 THE CHICAGO ACADEMY OF SCIENCES. 



Animal: Not examined. 



Distribution: Lilycash Creek, near Joliet. (Collected by 

 J. H. Handwerk.) 



Geological distribution : Unknown. 



Habitat: In a small creek, in soft mud. 



Remarks: This variety was referred to Dr. V. Sterki by 

 Mr. Handwerk, and considered by him to be an unusual form of 

 striatinum, but he did not consider it distinct from the typical 

 form. After examining a large number of specimens, the writer 

 has concluded that it is a form distinct enough for a specific 

 name. Its beautiful polished surface and inflated shell will at 



FIG. 137. 

 SPH/ERIUM LILYCASHENSE Baker. Natural size. 



once distinguish it from striatinum. It is shaped differently 

 from stamineum and the beak sculpture is very much finer. 



Another form is found associated with the variety which 

 is in a sense intermediate between the typical form and the 

 variety, having a more oval shell than the type, but not being 

 so much inflated; it is very dark chestnut or dark brown in color. 

 Several specimens of this form had the hinge wholly or partly 

 inverse. 



p. 120. 

 43. Calyculina transversa Say. 



This species has been found abundantly in the Desplaines 

 River (J. H. Handwerk), and in Lake Michigan (Dr. H. N. 

 Lyon). 



p. 126. 

 47. Pisidium abditum Haldeman. 



This species has been found in large numbers in Lilycash 

 Creek and at Smith's Bridge, eleven miles southwest of Joliet. 



