1918.] NATURAL SCIENCES OF PHILADELPHIA. 295 
Alt. 14 diam. 25 mm.; aperture 11.2x13.6 mm.; 42 whorls. 
Marble Peak, Santa Catalina Mountains, Arizona; type loc. 
Station 26, 1913, quartzite slide on Marble Peak. Also found at 
Station 3, 1911, slide above Apache mine; Station 4, 1911, top of 
ridge south of the Peak; Station 38, 1913, north side of Marble 
Peak; ‘Joliet Cave,” and other stations on the same mountain. 
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Fig. 6. Genitalia of Sonorella marmorarius, a, No. 109,077; b, c, No. 109,071; 
d, No. 109,039; e, No. 109,083; f, No. 109,084; g, No. 109,078. 
Genitalia (Fig. 6a-g). The penis is thin-walled, very weakly or 
usually not noticeably enlarged near the atrium, containing a slender 
tapering, corrugated papilla, half to two-thirds or more the length 
of penis. Epiphallus somewhat shorter than penis, typically ter- 
minating in a little flagellum, but this is often rudimentary or wanting. 
Penial retractor long, inserted on apex of penis and base of epiphallus. 
The vagina is but little shorter than the penis. Lengths of the 
organs in mm. follow, the specimens all from stations on Marble 
Peak: 
