434 The Molluscan Family Planorbidae 



PLATE 99 



Shells of Planorbidae 



1. Hclisoma ienue applanatutn (\on Martens). Near Vallecitos, Lower California. Im- 

 mature. U.S.N.M., 162654. 



2,3. Hclifioma tome applanatum (von Martens). Yaqui River, near Ciudad Obregon, 

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



4-8. Hvlixoma tenue sinuosiini (Bonnet). Santa Cruz River, Tucson, Arizona. Imma- 

 ture. U.S.N.M., 130237. 



9,10. Hclisoma tenue sinuosum (Bonnet). Rio Grande, El Paso, Texas. Immature. 

 U.S.N.M., 130239. 



11-15. Helisoma tenue calif orniense F. C. Baker. Bixby, Los Angeles Co., California. 

 Immature. U.S.N.M., 174048. 



16-19. Hclisoma tenue strebclianum (F. and C). Penasco, 5 miles north of San Luis 

 Potosi, Mexico. Immature. LT.S.N.M., 251815. 



20-24. Hclisoma caribacum guatcmalcnsc (Clessin). Reservoirs 4 miles north of 

 Guatemala City, Guatemala. U.M., 83490. 



25. Hclisoma tenue strebelianum (F. and C). Tamaulipus, Mexico. LT.S.N.M., 109916. 



26. Hclisoma tenue strebelia7ium (F. and C). Coy River, San Luis Potosi, Mexico. 



B3921. 



27-30. Hclisoma tenue strcbelianuia (F. and C). Alta Mira, Tamaulijius, Mexico. 

 U.S.N.M., 251807. 



31. Hclisoma caribacum (Orb.). Naranjo, (Juatemala. Varying toward Hclisoma cari- 

 bacum guatcmalense. LT.M., 83487. 



32-36. Helisoma caribaeu}7i guatemalense (Clessin). Nicaragua. U.M., 83485. 



All figures are enlarged about 1^/4 diameters 



