CH^ENAXIS. 



"Length 3.25, diam. 1.8 mm.; 5% whorls (smallest nor- 

 mal shell)." 



Arizona: foothills of the Plmnosa Range,, about 8 miles 

 east of Quartzsite, Yuma Co. (Geo. S. Hutson) ; debris of 

 Salt Eiver, Tempe, Maricopa Co. ; flood debris at west end of 

 Congress St., Tucson (Pilsbry and Ferriss). 



Bifidaria tuba subsp. intuscostata CLAPP, Nautilus, xxii, 

 Dee. 1908, pp. 76, 96, pi. 7, figs. 1-11. 



The main distinctive character of this species is the long, 

 spirally ascending supracolumellar lamella, which is wanting 

 in C. tuba. It is also, in the main, longer and more cylin- 

 drical than tuba. At Tucson it occurs with the latter in 

 storm debris apparently washed out of the Tumamoc Hills. 

 Dr. Clapp has figured several curious abnormal shells found 

 in the original lot. 



Figs. 5-8. Abnormal specimens of C. intuscostata. 



The specimens from Tucson and Tempe are typical in struc- 

 ture. It is rare at Tempe, where the largest taken measures, 

 length 4, diam. 1.7 mm. 



2a. Form brevicostata, new form. PL 9, figs. 4, 5. The 

 shell is smaller and tapers more upwards than B. intuscos- 

 tata, and the spiral supracolumellar lamella is only about one 

 whorl long. Length 3.25, diam. above aperture 1.6 mm. 



Tempe, Arizona, in drift of Salt Eiver (Pilsbry and Fer- 

 riss, Ashmun). 



A fragmentary specimen of this was figured in Proc. A. 

 N. S. Phila., 1906, p. 146, fig. 7. 



