Sterki: North American Sph.eriid.e. 433 



Few adult or adolescent specimens are of a "bright golden" color 

 and not many are "greenish yellow," as is said in Prime's description; 

 generally they are light to dark corneous, or grayish. Specimens of 

 various other Sphccria have been named "aureum'' on account of 

 their yellow color. 



Habitat. — The original specimens were supposed to be from Lake 

 Superior; apparently the same SphcEriiim is found in the Upper 

 Mississippi Valley, in Illinois, Iowa, South Dakota, Missouri, and as 

 far east as northwestern Ohio. A somewhat different form, but 

 probably not distinct, comes from southern IVIissouri, Arkansas, and 

 Kansas. 



7. Sphaerium lineatum Sterki. 



Natililus, XXIII, 1910, p. 142. 



Habitat. — Indiana, Illinois, Michigan. 



8. Sphaerium solidulum (Prime). 



Cyclas solidiila Prime, Boston Proc, 1851, p. 158. 

 Sphcerium solidulum Prime, Mon. Corb., 1865, p. 36. 



Habitat. — Mississippi Valley and eastward; very variable and not 

 yet clearly definable, though good material from many places is at 

 hand. Typical and near-typical forms occur in Ohio, Indiana, 

 Illinois, Michigan, and Kentucky, in rivers and creeks. From Ohio 

 eastward it becomes apparently scarcer, and is represented by smaller 

 forms, some of them barely recognizable. Westward (Iowa) and 

 southward (Alabama) there are found other different, yet apparently 

 conspecific forms, more elongate, with finer striae, and slighter shells 

 and hinges. A peculiar lacustrine form from Lake Michigan may be 

 of this species, though of a very different shape. 



Fossil. — Ohio. 



9. Sphserium stamineum (Conrad). 



Cyclas slaminea Conrad, American Journ. Sci., XXV, 1834, p. 342. 

 Spharium stamineum Prime, Mon. Corb., 1865, p. 38. 



Very variable, more so than any other species, and several extreme 

 forms appear to be distinct. It is rather a "form-cycle" than a 

 species in the current sense. 



Habitat. — Mississippi \'alley and eastward (rare east of the Appa- 

 lachians) ; Manitoba. 



Fossil. — New York, Ohio, Michigan, Illinois. 



