localities give but a partial idea of its probable distribution in 

 this region. The species has passed in the literature under a 

 variety of names; the slender spire, rather inflated whorls, 

 and round aperture are characteristic, however. While gen- 

 erally but 3-5 mm. in length, it often attains a much larger size. 



Europe, Siberia; North America south into Mexico and 

 Baja California. 



Los Angeles System : Three reservoirs, Bardsdale, Santa 

 Clara River Valley (H. Hannibal) ; mouth of Santa Ynez 

 Canon, Santa Monica Mountains (H. Hannibal) ; Ilemmet's 

 spring, San Franciscquito Canon, five miles south of Elizabeth 

 Lake, Tejon Pass (H. Hannibal) ; spring, one-fourth mile north 

 of German, Tejon Pass (H. Hannibal). 



Green houses, Redlands (S. S. Berry) fide Berry. 



Mountain Home Gulch, one and one-half miles below Glen 

 Martin, San Bernardino Mountains (H. Hannibal) ; San Ja- 

 cinto Canon, South Fork dam, San Jacinto Mountains (H. Han- 

 nibal). 



Near Ensenada, Lat. 31° 51', Baja California (C. R. Or- 

 cutt ) fide Orcutt. 



Arizona System: Ash Canon, Iluachuca Mountains (Fer- 

 riss and Daniels) fide Pilsbry and Ferriss; Santa Cruz River, 

 Tucson (E. A. Mearns) fide Dall. 



PLANORBIDAE. 



Planorbis trivolvis Say, Nich. Encyc. (1st Ed.) II, 1817, 

 PL II, 2; P. tumidus Pfeiffer, in Weigm. Archiv., 1839, 351; P. 

 amnion Gould, Proc. Bos. Soc. Nat. Hist. V, 1855, 129; P. 

 tumens Carpenter, Cat. Reigen Shells, 1857, 181; *P. trivolvis 

 Binney, L. & F. W. Shells, N. Am. II, 1865, 115, fig. 194-201 : 

 *P. trivolvis Hannibal, W. Coast Shells, 1910, 309, fig. 292-3. 



An exceedingly variable species common, particularly in 

 ponds and marshy creeks, over nearly all North America and 

 the West Indies. An enumeration of all the names applied to 

 it would require several pages. 



Los Angeles System : Artificial pond, hill three miles west 

 of Santa Barbara on Goleta road, foothills of Santa Ynez 

 Mountains (II. Hannibal); Hope Ranch Lake, Santa Barbara 

 (II. Hannibal). 



Ballona swamp between Inglewood and Venice, Los An- 

 geles 'Coastal plain (II. Hannibal) ; swamp between Palms and 

 Cienaga (II. Hannibal) ; swamp, Sherman (II. Hannibal) ; res- 

 ervoir, hills north of Soldiers' Home (II. Hannibal) ; Los An- 

 geles (II. Hemphill) fide Stearns; Bouton sloughs, Bixby (II. 

 Hemphill) (H. Hannibal) ; pond near P. E. R. R. south foot 

 of Signal Hill (II. Hannibal) ; AVillows Creek, Long Beach 

 (H. Hannibal) ; (extinct) field near Domingues (II. Hemp- 

 hill) ; Compton Creek between Albida and Lynwood (II. Han- 

 nibal) (Quaternary) Point San Pedro (D. and R. Arnold) fide 



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