430 The Molluscan Family Planorbidae 



PLATE 97 



Shells of Planorbidae 



1-4. Helisoma tenue (Philippi). Platpa near City of Mexico, Mexico. Tj'pe locality. 

 U.S.N.M., 160175. 



5. Helisorna tenue (Philippi). Laguna de Tamos, near Tampico. Vera Cruz, Mexico. 



U.S.N.M., 467437. 



6. Helisoma tenue (Philippi). Toluca, Mexico. U.S.N .M., 185942. 



7,8. Helisoma tenue (Philippi). Lake Texcoco, near City of Mexico, Mexico. M.C.Z. 



9. Helisoma tenue (Philippi). Vera Cruz. Strebel Coll. U.S.N.M., 10585. 



10. Helisoma tenue (Philijipi). Sources of Rio Lerma, Valley of Toluca, Mexico. 



U.S.N.M., 467433. 



11. Helisoma tenue (Philippi). Orizaba, Mexico. U.S.X.M., 22009. 



12. Helisoma tenue bourcardi (C. and F.). City of Mexico, Mexico. U.S.N.M., 8506. 

 13-17. Helisoma tenue bourcardi (C. and F.). City of Mexico, Mexico. U.S.N.M., 



26453. 

 18-25. Helisoma tenue craggeratum (von Martens). Lake Patzcuaro, State of Michoa- 



can, Mexico. Type locality. U.S.N.M., 467462. 

 26-28. Helisoma tennc applanatum (von Marten.s). Lanos River, Chichuachua, Mexico. 



U.S.N.M., 16252. 



All figures are enlarged about P/o diameters 



