Page:Land Mollusca of North America (north of Mexico) Vol. I Part 1 277-end.pdf/16



differences are too slight and inconstant to call for separation from typical marmorarius.

(Marmorarius, a worker in marble.)

Sonorella marmorarius limifontis Pilsbry & Ferriss Fig. 160 d.

Sonorella marmorarius limifontis Pilsbry & Ferriss, 1919. Proc. Acad. Nat. Sci. Phila., for 1918. p. 296. pl. 3. figs. 5-5b.

The shell is depressed, openly umbilicate, the width of umbilicus contained slightly over 6 times in that of the shell; whitish, faintly buff near the suture and on the spire, having the usual chestnut-brown band. Last whorl wide, very deeply descending in front. Surface glossy, weakly marked with growth-lines as in related species of the hachitana group, and showing weak traces of impressed spiral lines on the upper surface of the last whorl. The last whorl descends deeply and abruptly in front. The aperture is very oblique, rounded-oval. Peristome somewhat expanded, slightly thickened within.

Height 13.3 mm., diameter 22.5 mm.; 5 whorls. Type.

Height 15.5 mm., diameter 26.5 mm.; 5 whorls (exceptionally large).

Arizona: Santa Catalina Mountains, bluffs near Mud Springs, in Pine Canyon (J. H. Ferriss), Type 109500 A.N.S.P.

The last whorl descends more than in S. marmorarius, the aperture is more oblique, and the color of adults is paler. The immature shells have more of a cinnamon tint than the adults.

The spiral lines mentioned in the description are usually very faint, often scarcely discernible, but in the largest example they are quite distinct. The umbilicus sometimes varies to somewhat smaller than in the type specimens, 6-2/3 times in the diameter.

Mud Springs, in Pine Canyon, a branch of Sabino above Sabino Basin, is a walled hole in the mud. It is on the trail from Sabino Basin to Soldier's Camp, the elevation about 7,000 feet. It is in the pine zone. The Sonorella was found in the first rocks cast of the spring along the trail. Also at the foot of a high cliff, in stratified " porphyry," in a ravine heavily wooded with cypress (Cupressus arizonica), about a mile southeast of the springs.

(Limifontis, of a mud spring.)

Sonorella tortillita Pilsbry & Ferriss Fig. 162.

Sonorella tortillita Pilsbry & Ferriss, 1919, Proc. Acad. Nat. Sci. Phila., for 1918. 70: 299. pl. 5. figs. 4-4b; text-fig. 8.

The shell is umbilicate, width of umbilicus contained nearly 8 times in that of the shell, pinkish buff, fading to white around the umbilicus and paler near the chestnut-brown band which revolves above the periphery of the last whorl and shows very narrowly above the suture on most of the penult whorl. The surface is glossy: embryonic shell about 1: whorls, the first half whorl having some radial wrinkles, the rest of the embryonic portion closely irregularly granulose, and having fine, often rather indistinct,

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