358 MEMOIRS OF THE CARNEGIE MUSEUM. 



EXPLANATION OF PLATE VIII. 



All figures are three-fourths natural size, a, lateral view; h, dorsal view. 



Fig. 1. EUiptio niger (Rafinesque). Normal specimen of medium size, from the 

 Ohio River, Industry, Beaver Co., Pennsylvania, collected September 8, 1908; C. M. 

 Cat. No. 6L3781. 



Fig. 2. EUiptio dilatatus (Rafinesque). Gravid female of medium size, diameter 

 29 percent of length, from the Allegheny River, Godfrey, Armstrong Co., Pennsylvania, 

 collected July 27, 1910; C. M. Cat. No. 61.4618. 



Fig. 3. EUiptio dilatatus sterkii Grier. Female, one of the types, which, however, 

 is not much swollen, the diameter being only 32 percent of the length. From Lake 

 Erie, Presque Isle Bay, Erie, Erie Co., Pennsylvania, collected July 12, 1910; C. M. 

 Cat. No. 61.4628. 



Fig. 4. EUiptio violaceus (Spengler). Normal .specimen as found in smaller 

 streams, from a small tributary of Lizard Creek, West Penn, Schuylkill Co., Pennsylvania, 

 collected May 4, 1909; C. M. Cat. No. 61.4308. 



Fig. 5. EUiptio violaceus (Spengler). Strongly compressed form with rough 

 epidermis corresponding to the form called jejunus by Lea, from a mill-race of Crooked 

 Creek, Tioga, Tioga Co., Pennsylvania, collected August 19, 1909; C. M. Cat. No. 

 61.4312. 



Fig. 6. EUiptio cupreus (Rafinesque). Specimen of medium size from Gre^ 

 Tonoloway Creek, Thompson Township, Fulton Co., Pennsylvania, collected September 

 5, 1909; C. M. Cat. No. 61.4322. 



Fig. 7. EUiptio fisherianus (Lea). Normal specimen of medium size from Chop- 

 tank Mills, Kent Co., Delaware, collected by S. N. Rhoads, June, 1903; C. M. Cat. No, 

 61.4645. 



