PLANORBIS. 



191 



3. PLANORBIS TUMENS, Carpenter. 



Plate 5, fig. 5, 6. 



Shell rapidly swelling, small, horn or red- 

 dish smoke-colored ; whorls four or five, with 

 light waving strise; sutures deeply impressed; 

 on one side subangulate or subcarinate near 

 the suture, on the , other rounded ; umbilicus 

 very deep ; aperture with a sinuous edge, one 

 side standing out above, flattened below, the 

 other flattened above, produced below, capa- 

 cious and rounded ; labium very thin. 



Diam. 15, alt. 6-5 mill. 



Mazatlan, Lower California, Southern Cali- 

 fornia. 



The irregularity of the last whorl, as shown 

 in my figures, appears to be characteristic of 

 the species. 



(38) 



