42 THE NAUTILUS. 



A small. variety found on the exposed surface of stones in the swift 

 current, is remarkably depressed with a very large aperture. The 

 columella is broad and thickened its entire length ; it is sometimes 

 white instead of tinted and purple; the spire is very much depressed, 

 hardly extending beyond the body-whorl ; when placed aperture 

 down, the apex is low down on the right side. One of the largest 

 specimens measured over the columella, is .30 of an inch, the largest 

 measurement is .40 of an inch. When placed aperture down, the 

 height is .21 ; extreme length of aperture .30 of an inch, width from 

 center of columella to outer lip .19 of an inch. 



It seems to me that the forms described as A. elegans and A. for- 

 mosa Lea, more properly belong in the synonym of A. picta instead 

 of ampla. Young specimens referable to these varieties appear to be 

 only color varieties of young picta. 



A. melanoides Conrad. This unpretentious species was found on 

 pebbles in strong current in Black Warrior River at a bridge near 

 Warrior. The spire is more elevated than usual with the species of this 

 genus, the perfect ones have four whorls, the spire of most specimens 

 is eroded, only two whorls left. A few are banded, but most have no 

 indication of bands. Mature specimens with eroded spire measure 

 .40 to .45 length and .28 to .30 inch diameter. Columella a little 

 thickened at the base and the aperture angulated at the juncture of 

 the columella and outer lip. 



A. picta Conrad. Common at Fort William Shoals, Wetumpka 

 and vicinity. A very variable species, smooth, sometimes corded or 

 plicate, or both. The bands extremely variable. The most common 

 form is eight to twelve narrow bands made up of dots and dashes. 

 These may be placed so as to form diagonal stripes as in A. zebra 

 and ftammata, and in some instances these diagonal bands are so 

 strong as to blur the revolving lines of dashes. The bands are often 

 continuous and number from two to twelve, or the two characters of 

 bands may be alternate on the same specimen. Many are imper- 

 fectly banded and a few without bands, occasionally one in purple. 

 The columella is often purple or tinged with that color; the prevail- 

 ing color is white, the plicae are often waves or folds. The shll may 

 be globose. In old specimens the body-whorl is often compressed 

 above the periphery, sometimes giving the shell a distorted appear- 

 ance. 



A. plicata Con. Black Warrior River at Warrior, Ala., common. 



