946 ZOOLOGY MOLLUSC A. 



Oregon and California only. My friend Mr. G. W. Tryon considers the 

 presence of it in Utah as a valuable fact indicating a much greater dis- 

 tribution than was formerly known. 



FAM. PLANOKBIDAE. 



Genus PLANORBIS, Guettard. 

 Subgeuus Helisoma, Swainson. 

 PLANORBIS TEJtVOLVIS, Say. 



Planorbis trivolvis, SAY, Nicb. Eucycl., 1817-19, pi. ii, f. 2. Id., Am. Concli., pt. vi, 

 18,34, pi. liv, f. 2. Id, Biiincy's ed., 44, pi. Ixx, f. 13; pi. liv, f. 2. DEKAY, 

 N. Y. Moll., 1843, pi. iv, f. 59 a, fr. GOULD, Invert, Mass., 1841, 201, f. 131. 

 HALD., Mon., 1844, 13, pi. ii, figs. 4-7. ADAMS, Verm. Moll.. 1842, 154. 

 KiisTER, Chemnitz, ed. 2, 53, pi. v, tigs. 4-6; pi. vi, figs. 1-G, 20-25. 

 POTIEZ & MICHAUD, Gal. des Moll., i, 214, pi. xxi, tigs. 19-21. ANON., 

 Can. Nat., ii, 1857, 202, f. . BINNEY, Land & Fresh Water Shells N. A., 

 pt. ii, 1865, 116. EGBERTS, U. S. Geol. Surv. Terr., 1870,468. 



Bulla jlm-iatilis, SAY, Jour. Acad. Nat. Sci. Phila., ii, 178. SAY, Conch., Binuey's 

 ed., 71. 



Planorbis regularis, LEA, Trans. Am. Phil. Soc. Phila., ix, 6. Id., ib., Proc., ii, 1841, 

 32. Id, i'j., Ohs., iv, <i. 



Planorbis meyaxtoma, DEKAY, N. Y. Moll., 1843. 61, pi. iv, figs. 60, 61. 



Phijua planorbula, DE!VAY, N. Y 7 . Moll., 1843, 76, pi. v, f. 83. 



Planorbis corpulent us, DEKAY, N. Y. Moll., 1843, 64, pi. xiii, f. 185. WniTTEMORE, 

 Am. Jour. Sci. & Arts [1], xxxviii, 193. 



V Planorhis proboscideits, POTIEZ & MICIIAUD. Gal. des Moll., i, 1838, 213, pi. xxv, figs. 

 13-15. 



Pldnorbix )n<-ro.stinux, WuiTEAVES, Can. Nat., viii, 1863, 113, f. . 



Pliuiorhiti trirolrix \--.\i: falln.i; HALD., Mon., 1844, pi. iii, tigs. 1-3. 



Plaiwrbix IcnttiK, GOULD, Invert,, 1841, 202, f. 132. 



Helix trirolrix, EATON, Zoiil. Text Book, 1826, 194. 



Cochlea triiun-orbum, LTSTER, Conch., pi. cxl, f. 46. PETIVER, Gazophyl., pi. cvi, f. 16. 



A very common species, being found everywhere throughout the 

 United States and Canada. In but one locality in Utah was it found liv- 

 ing, viz, the ditches near Salt Lake City. 



At Panquitch Lake, Southern Utah, immense numbers of these shells 



