432 The Molluscan Family Planorhidae 



PLATE 98 



Shells of Planorbidae 



1. Helisoma tenue applanatam (von Martens). Orizaba, Mexico. Strebel Coll. 



U.S.N.M., 10538. 

 2-6. Helisoma tenue applanatum (von Martens). Yaqui River, near Cimlad Obregon, 



Sonora, Mexico. U.S.N.M., 467429. 

 7,8. Helisoma tenue applanatuni (von Martens). Mazatlan, Mexico. Lea Coll. 



U.S.N.M., 121192. 

 9-13. Helisoma tenue sinuosum (Bonnet). Santa Cruz River, Tucson, Arizona. In 



stream bed. U.S.N.M., 130237. 

 14-. Helisoma tenue sinuosum (Bonnet). Soroyta Creek, Sonora, Mexico. U.S.N. M., 



130229. 



15. Helisoma tenue sinuosum (Bonnet). Albuquerque, New Mexico. 5000 ft. altitude. 



U.S.N.M., 134552. 



16, 17. Helisoma tenue caUforniense F. C. Baker. Santa Cruz, California. U.S.N.M., 



47571. 

 18. Helisoma tenue calijorniensc F. C. Baker. Santa Cruz, California. U.S.N. M., 47572. 

 19-21. Helisoma tenue calijorniense F. C. Baker. Crystal Creek, San Jose, California. 



U.S.N.M., 32111. 



22. Helisoma tenue ealijorniensc F. C. Baker. Santa Cruz Mts., 4 miles from Los 

 Gatos, California. U.S.N.M., 75437. 



23,24. Helisoma tenue calijorniense F. C. Baker. Guadeloupe Creek, San Jose, Cali- 

 fornia. Paratypes. B3262. 



25. Helisoma tenue sinuosum (Bonnet). Rio Grande. El Paso, Texas. Immature. 



U.S.N.M., 130239. 



26. Helisoma tenue calijorniense F. C. Baker. Bixby, Los Angeles Co., California. 



Immature. B3227. 



Figures 25 and 26 show differences in spire whorls and 

 sculpture of the two ^'arieties 



All figures are enlarged about V/^. diameters 



