Arizona System: (semifossil) Colorado Desert (W. P. 

 Blake) fide Gould. 



Colorado River, Yuma, fide Cooper; San Bernardino River 

 (E. A. Mearns) fide Dall. 



CORNEOCYCLADIDAE. 



Corneocyclas compressa (Prime). 



Pisidmm compressum Prime, Proc. Bos. Soc. Nat. Hist. 

 IV, 1851, 164; *Mon. Am. Corbie., 1865, 64, fig. 67; *P. com- 

 pressum Hannibal, W. Coast Shells, 1910, 306, PI. I, 2. 



Dall (Tr. Wagn. Inst. Ill, 4, 1903, p. 1439-60) has shown 

 that Corneocyclas is the proper name to use for this group of 

 the old genus Pisidium. 



C. compressa is deeidedly sporadic in occurrence in the 

 present region, due to the general absence of lakes, its most 

 frequent habitat. 



All North America south to Mexico, into which it extends 

 but a short distance. 



Los Angeles System: Ventura County (H. Hemphill) fide 

 Dall. 



Arizona System: San Bernardino River, Arizona (E. A. 

 Mearns) fide Dall. 

 Corneocyclas pulchella (Jenys). 



The English name pulchella of -Jenys, a clergyman noted 

 for his studies among these small bivalves, takes priority over 

 the familiar American abdita by some nine years. The species 

 may have been named even earlier on the Continent but the 

 European Corneocyclades are imperfectly known. Through 

 the effort of several writers an almost endless number of spe- 

 cies and varieties distinguished from pulchella by slight vari- 

 ations of shape and color have been recognized in the United 

 States. Since the epidermis of all the Corneocyclades is straw- 

 colored when treated with Oxalic acid to remove the iron salts 

 mechanically deposited in it (doubtless as a protective de- 

 vice), the writer questions whether these cannot all be writ- 

 ten as synonyms. 



All North America, Europe, Asia. 



Los Angeles System: Spring, Garapitos Canon one-fourth 

 mile above Topanga P. 0., Santa Monica Mountains (II. Han- 

 nibal) ; Hemmet's spring, San Franciscquito Canon, five miles 

 south of Elizabeth Lake, Te.jon Pass (H. Hannibal); spring 

 one-fourth mile north of German, Tejon Pass (H. Hannibal). 



Swamp between Palms and Cienaga, Los Angeles Coastal 

 Plain (II. Hannibal) ; slough half-mile west of Santa Fe Springs, 

 Whittier (II. Hannibal). 



Big Meadows Cienaga, Santa Ana Canon, San Bernar- 

 dino Mountains (II. Hannibal) ; cienaga at forks of Cienaga 

 Seco Creek, Santa Anna Canon (H. Hannibal); Cienaga Seco, 



