Page:Land Mollusca of North America (north of Mexico) Vol. I Part 1 277-end.pdf/31

 vestigial or wanting flagellum. Neighboring Sonorellas southward in the Chiricahuas differ by their apical sculpture and genitalia.

In the type lot the diameter varies from 22.8 to 26 mm. In a colony from Rough Mountain the size runs from 15.5 to 20.5 mm. A small shell from near the type locality measures 9.8 x 16.3 mm., 4| whorls (Fig. 173, lower left).

The shells from Rough Mountain and Wood Mountain usually show numerous spiral striae on the upper surface of the last whorl, but this character is variable; in some shells of each lot no spiral striae can be made out.

Measurements of the genitalia of specimens from 5 localities follow:

Penis 5 7 4.5 5 4.6 mm.

Verge 7 4 4 2.6 2.6 mm.

Epiphallus 4.5 3.5 5 5 2.7 mm.

Vagina 8 8 6 5 7 mm.

Spermatheca .. 26 24 20 .. mm.

Shell, diam 25 25.5 18.5 19.5 20 mm.

Fig. 175. Pallial region of Sonorella optata, two individuals K, kidney; P, pericardium.

The lung (Fig. 175, right fig.) has venation much as in S. compar. The secondary ureter is open throughout, being defined by a thread-like ridge only. Length of lung 26, of kidney 14, of pericardium 5 mm. In one of several examined the pulmonary vein has a large branch on the cardiac side,

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