368 PROCEEDINGS OF THE ACADEMY OF [June, 



Pilsbry and are not plotted on the map. They are believed to be 

 east oi the granitic spur (dyke) on the north side of Tweed Canyon. 



Station 23a. Small hill in bottom of Tweed amphitheatre near 

 an abandoned arrastra. 



Station 24. Gully on mesa, running westward out of Fourr ranch. 



Station 25. Foothill west of Fourr ranch. 



Station 26. Gully at south fence of Fourr ranch. 



Station 27. First ravine west of Cataract Branch in the igneous 

 southern side of Tweed Canyon. 



Station 28. Bear Gulch, half way down. 



Station 29. Bear Gulch, near its head. 



Station 30. Ridge west of Bear Gulch. 



Stations 31, 32. East side of Soren Gulch. 



Station 33. West side of Soren Gulch. 



Station 34. Small limestone hill in Middlemarch Canyon. 



Station 35. Cochise Peak. 



Stations 36, 37. Small limestone hills eastward on mesa at mouth 

 of Middlemarch Canyon. 



Station 38. North side of north ridge of Tweed amphitheatre, 

 I mile west of Signal Peak. 



Stations 39-42. Successive stations between the northern crest 

 of Tweed amphitheatre and the northern foothills of the range. 



HELICID^. 



Sonorella ferrissi Pilsbry, n. sp. PI. \lll, figs. 3, 3a, 3b. 



The shell is strongly depressed, umbilicate (the width of umbilicus 

 contained six times in the diameter of the shell), rather sohd; of a 

 pale brown tint, between cinnamon and wood-brown, fading around 

 the umbilicus, having broad white bands above and below the 

 narrow chestnut-brown shoulder band and crossed by one or several 

 whitish streaks, reminiscent of former peristomes. The surface is 

 semimat. The initial one-fourth whorl is smooth; a brief stage of 

 coarse radial wrinkles ensues, followed by fine, short, interrupted 

 radial wrinkles, so short as to be papillae near the upper suture, and 

 sparse, short elevations, arranged in spiral, forwardly descending 

 series. On the second whorl these elevations become distinct, rather 

 regular papillae, which persist, in some examples, upon the third 

 whorl. The last whorl has fine striae and microscopic wrinkling. 

 The spire is but slightly convex. The whorls increase slowly, the 

 last descends a little in front and is rounded at the periphery and 

 base. The peristome expands very slightly in its lower half, and its 

 edge has a rusty tint. It is thickened within by a rather wide but 

 thin white callus, which shows as an opaque buff border behind the 

 lip. The columellar termination is slightly dilated, and the parietal 

 callus moderately thick in fully mature or old individuals. 



