Page:Land Mollusca of North America (north of Mexico) Vol. I Part 1 277-end.pdf/10

 Sonorella walkeri Pilsbry & Ferriss Fig. 156.

Sonorella walkeri Pilsbry & Ferriss, 1915, Proc. Acad. Nat. Sci. Phila., p. 394, pl. 9. figs. 4-4b.

Sonorella montana Pilsbry & Ferriss, 1919, Nautilus, 33: 19.

Sonorella walkeri montana Pilsbry & Ferriss, 1923, Proc. Acad. Nat. Sci. Phila., 75: 68, pl. 1, fig. 11; text-fig. 1.

Sonorella walkeri aguacalientensis Pilsbry & Ferriss. 1923, Proc. Acad. Nat. Sci. Phila., 75:68.

The shell is umbilicate (the width of umbilicus contained about 9 times in the diameter of the shell), rather solid, pale cinnamon, fading to white around the umbilicus and on both sides of the chestnut-brown shoulder band. The surface is glossy, lightly marked with growth lines, and under a strong lens showing impressed spiral lines on the upper surface of the last whorl (lacking, however, in many individuals). Initial 1/3 whorl radially

Fig. 156. Sonorella walkeri.

rippled, granulation then beginning, the last 2/3 whorl of the embryonic shell having close ascending spiral threads, the intervals densely wrinkled radially. Spire very low conic. Whorls 4-2/3, the last descending in front. The aperture is rounded oval; peristome narrowly expanding, inconspicuously brown-edged, slightly thickened within, the margins converging, joined by a thin, brownish-edged parietal callus.

Height 14 mm., diameter 23 mm.; umbilicus 2.6 mm.; aperture 12 x 13 mm.

Genitalia (Fig. 157: 1-3, 5, 5a). The penis is small and slender, at the base enclosed in a short but thick sheath. Verge cylindric, more than half the length of penis, tapering distally to a blunt or a somewhat pointed end. Retractor muscle inserted on the epiphallus near its base. Epiphallus as long as the penis or somewhat longer, terminating in a minute, bud-like flagellum. Lower part of the vas deferens large, its diameter equal to or exceeding that of the epiphallus. Vagina usually about twice the length of the penis. Six specimens from 4 localities measure:

Penis 4.7 5 4 4.3 4 7 mm.

Verge 2.3 3 2.3 2.8 3 5 mm.

Epiphallus 5 5 6 7.3 6.5 6.7 mm.

Flagellum 1 minute minute minute 0.7 minute

Vagina 8 7 10 10 7.5 7 mm.

Arizona: Santa Rita Mountains, the type from Walnut Branch of Agua Caliente Canyon, at about 6000 feet, Type 112164 A.N.S.P. (Ferriss, Daniels and Pilsbry, 1910). Also taken in "Soldier Canyon," at about

Fig. 157. 1-3. 5, 5a, Sonorella walkeri. 4, 6, 7, S. clappi. epi., epiphallus; fl., flagellum; pp., verge; p.r., penial retractor; v.d., vas deferens.

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