THE NAUTILUS. 137 



terminating with an inconspicuous whitish line ; the first ^ whorl is 

 depressed and highly polished ; the remaining embryonic whorls are 

 evenly and densely covered with elongate-oval papillae arranged in 

 spiral lines. In the following 1^-2 whorls, beginning the neanic 

 stage, the epiconch bears exceedingly delicate, very short hairs ar- 

 ranged in obliquely descending series, but less regular than the 

 papillae of the embryonic whorls. These are entirely lost in mature 

 shells, although the hair-scars are generally visible on fresh speci- 

 mens. The body-whorl shows the usual slight growth-lines, but is 

 otherwise smooth except for varical impressions showing resting 

 periods, of which there are usually 2 on the body-whorl and others 

 clear up to the nuclear whorls. The body-whorl enlarges rapidly, 

 and is suddenly deflected and expanded at the aperture, which is 

 large, almost round, oblique, with a slightly reflected and thickened 

 margin ; lips widely expanded at the columella and partly reflected 

 over the umbilicus. Ends of lip converging, forming about four- 

 fifths of a circle. Gr. diam. 14^, lesser 11^, alt. 8 mm. Aperture 

 7 mm. high, 7 mm. wide. Umbilicus 2^ mm. 



The figured specimen measures, alt. 7.5, diam. 14 mm. The 

 largest and smallest shells that I have seen measure 15 and 12^ 

 mm. diam. respectively; both are dead shells. 



Collected by Geo. S. Hutson, after whom the species is named, 

 about 8 miles from Quartzsite, Yuma Co., Ariz., in the foothills, at 

 an alt. of about 1600 ft. 



Types, No. 5659 of my collection ; co-types, coll. A. N. S. P. 



The sculpture of the embryonic whorls of this beautiful little shell 

 puts it in the group of Sonorella wolcottiana Bartsch (Smiths. Misc. 

 Coll., xlvii, p. 187, pi. xxviii). A large series from young shells of 

 2^ whorls to adults show the sculpture and epiconch in all stages, 

 the latter being so thin and delicate, however, that it apparently 

 entirely disappears by the time the shell has completed the third 

 whorl. The shells are remarkably uniform in size and color, and 

 most fresh specimens show occasional translucent spots scattered 

 over the body-whorl. The resting periods are shown by well- 

 marked varical impressions at all stages of growth, as is common in 

 most species from a semi-arid region. The body of the animal is 

 intensely black, with a gray mantle. 



