520 THE CHICAGO ACADEMY OF SCIENCES. 



13. Pseudosuccinea columella (SAY). Blount Co., Tenn. (Walker Coll. 



12876). Approaches var. chalybea in form. 



14. Pseudosuccinea columella (SAY). Concord, Tenn. (Walker coll. 



12877). 



15. Pseudosuccinea columella (SAY). Schuylkill River, Tenn. (Coll. 



Walker). 



16-19. Pseudosuccinea columella (SAY). Lincoln Park, Chicago (23054). 

 20. Pseudosuccinea columella (SAY). DuBois, Ills. (23055). 

 Figures 4-20, slightly enlarged; 1-3, natural size. 



PLATE XXIV. 



Figures 1, 2. Pseudosuccinea columella (SAY). Pass Christian, Miss. (Coll. 

 Walker, 6157). 



3. Pseudosuccinea columella (SAY). Lake Jessup, Manatee Co., Fla. 



(23053). 



4. Pseudosuccinea columella (SAY). Washington, D. C. (Coll. Walker, 



18301). 



5. Pseudosuccinea columella chalybea ( GOULD). Pittsburgh, Penn. 



(23057). 



6-7. Pseudosuccinea columella chalybea (GOULD). Allegheny, Penn. 

 (Coll. Walker, 10476). 



8. Pseudosuccinea columella chalybea (GOULD). Kent, Ohio (23062). 



9. Pseudosuccinea columella chalybea ( GOULD). Cambridge, Mass. 



Type locality (Coll. Walker, 5893). 

 10-12. Pseudosuccinea columella chalybea ( GOULD). Cattaraugus Co., 



N. Y. (23067). 

 13. Pseudosuccinea columella chalybea ( GOULD). Cattaraugus Co., N. Y. 



(23065). 

 14-19. Pseudosuccinea columella casta (LEA). Bass Lake, Ind. (23064). 



20. Pseudosuccinea columella championi (VoN MARTENS). Palvon, Nic- 



aragua. Coll. Walker (17317). 



21. Pseudosuccinea francisca (POEY). Pinar del Rio Province, Cuba 



(24627). 

 22-27. Polyrhytis utahensis (CALL). Bear Lake, Utah. Hayden Survey, 



Phil. Acad. Sci. (62603). 

 All figures enlarged about 1^2 diameters (figure 21 enlarged 2 diameters). 



PLATE XXV. 



Figure 1. Bulimnea megasoma (SAY). Under surface of animal. Whitfield, 



Bull. Am. Mus. N. H., I, pi. 5, fig. 2. 



2. Bulimnea megasoma (SAY). Animal seen from the side, 1. c. fig. 3. 



3. Bulimnea megasoma (SAY). Oconto, Wis. (23095). 



4. Bulimnea megasoma (SAY). St. Croix River, Wis. (23094). 



5. Bulimnea megasoma (SAY). Manitowoc Co., Wis. (23100). 



6. Bulimnea megasoma (SAY). Minnesota (23096). 



7-8. Galba preblei (DALL). Lake Isle La Crosse, Athabaska (23717). 

 9-10. Galba preblei (DALL). Alaska Moll., pi. 1, figs. 1-2. TYPES. 

 Figures 7-8, enlarged about 2 diameters ; 9-10, slightly enlarged ; balance natural 



size. 



