464 BULLETIN 10 0, UNITED STATES NATIONAL MUSEUM 



COCHLOSTYLA (PROCHILUS) CUYOENSIS (Pfeiffer) 



The shell of this species varies much in size in the different races. 

 In all of them, however, it is slender, elongate-conic, and thin, never 

 ponderous. There is a great variation in color. The thin periostra- 

 cum varies from pale straw-color through orange-brown to deep 

 chocolate-brown and may be plain or marked by hydrophanous 

 fulgurations. A narrow dark-brown band may be present at the 

 summit, and another, usually a much more conspicuous one, may be 

 present at the periphery, and a third dark area about the umbilicus 

 may mark the shells or all these bands may be absent. In some there 

 is even an additional band between the umbilical dark area and the 

 periphery. The intensity of coloration of this brown band varies in 

 the different races as does the width thereof. All sorts of the elements 



