FOSSILS OF THE CARBONIFEROUS. 



263 



Genus ZAPTYCHIUS, n. g. 



Shell minute, elongate; aperture large, oblong, nearly vertical; outer 

 lip thin, columellar lip reflected, plicated. 



Surface of shell marked by slightly oblique longitudinal strias. 



Type: Zaptycliius carlo a aria. 



Zaptychius appears to have its nearest living ally in Auricula, although 

 differing in the form of the body volution and spire from the typical forms 

 of that genus ; the presence of the Auricula-like aperture and elongate shell, 

 vertically striated, afford the basis for a new generic description. 



Zaptychius carbonaria Walcott. 

 Zaptycliius carbonaria Walcott, 1883. Science, vol. ii, p. 808, fig. 1. 



Shell small, slender, the body volution having a length of about 6.5 T 

 and a greater diameter of 2.5 min ; aperture rather large, elon- 

 gate, narrow posteriorly and broadly rounded in front; col- 

 umellar lip thickened anteriorly, the thickened portion curv- 

 ing inward opposite the umbilical chink to form a rounded 

 plication or ridge on the lip, which is reflected back on the 

 volution and marked by a second tooth-like plication pro- 

 jecting a short distance out into the aperture a little posterior 

 to the first. The number of volutions is unknown. 



Surface of the shell marked by even, equidistant, nearly 

 vertical stria3 that distinctly define the interspaces between 

 them. 



The form of the spire above the portion of the volution 

 preceding the body volution is unknown, although from the type"Bpecimen, xs. 

 character of that preserved and the presence of a trace of a volution 3.5 mm 

 above the body volution, it was probably more or less slender and elongate. 



Formation and locality. Lower portion of the Carboniferous formation, 

 in a chocolate-colored limestone, associated with Physa prisca 

 ria f Powelli, Eureka District, Nevada. 



