ZOOLOGY. MOLLUSCA. 195 



F(ECILOZONITES. 



Cleueric characters: Shell helicoid, suht.nxhiforra, depressed 

 conic, or subdiscoidul, perforate or umbilieato, obliquely striate, 

 ornanioiited with radiating zigzag flaramules or spiral bands 

 of chostmit color on aUghtor ground ; whorls numerous (7-10)^ 

 very slowly widening ; ?)ody-wliorl more or less flattened or 

 compressed below the usually cavinate periphery, not descend- 

 ing anteriorly; aperture more or less irregularly lunate; peris- 

 tome simple, the columellar margin slightlj^ expanded and 

 thickened with a white callus which encircles the pillar within. 

 Animal similar in form to Hdix ; foot narrow, short posteriorly, 

 scarcely reaching behind the shell, and without longitudinal 

 furrows above its margin or caudal mucous jioro ; orifice of geni- 

 talia on the right side of neck, near to, but not under, the mantle ; 

 mantle margin simple ; jaw like that of Limax, very thin, 

 arcuate, with a broad blunt median projection anteriorly ; 

 radula with tricuspid central teeth having quadrate basal 

 plates, the central cusps projecting beyond the anterior mar- 

 gins of the basal plates, the si<le cusps rather short, with well 

 reflexed cutting points; lateral teeth similar but asymmetrical, 

 lacking the inner cusps ; marginal teeth aculeate, with simple 

 thorn-shaped cusps and oval basal plates. 



It will be seen by the above definition that the genus cannot 

 be included in any of the groups with which its species have 

 been associated by autlioi-s ; the zonitoid dentition at once re- 

 moves it from the Heficid.r, and the absence of a caudal 

 mucous pore, the more anterior position of the orifice of the 

 genitalia and the coloration of the shell, separate it from 

 ZoiiUes and its subgenera. 



The relationship of the species of PoecUozonites to one an- 

 other is shown by the similarity of the radulte and jaws, and 

 of the external characters of the animal; in the shells, 

 wiiich at fii-st glance seem to be a heterogenous assemblage, by 

 the callus which coats the columella, the compression of the 

 whorl below the periphery, and especially by the color-pattern, 



