ZONITID^. 25 



costulately strigate above, rather smooth below; whorls 7-8|-, 

 closely revolving, the last convex at the base ; aperture lunar ; 

 peristome simple, thin, with a callous ring within. H. stephano- 

 phora^ Desh. (xciv, 13). Madeira. 



ACTTNARiA, Pfeiffer, 1855. Not characterized. 4 sp. India. 

 H. Pirrieana^ Pfr. 



PUNCTUM, Morse, 1864. Buccal plate composed of sixteen 

 distinct oblong laminae ; the teeth of the radula are quadrangular 

 plates with rather short denticles, similar to Carj'chium. Shell 

 as in H3'alina. H. minutissima^ Lea. United States. 



MACROCYCLis, Beck,183Y. Shell rather thin, widely umbilicated, 

 depressed ; the last whorl declining toward the aperture ; aper- 

 ture oval-roiiuded ; peristome simple, sharp, the extremities 

 approaching and the lower somewhat reflected. Z. la,xata^ Per. 

 (xciii, 93). Chili. 21 sp. California, Mexico, West Indies, Chili. 



SELENiTES, Fisclicr. Shell smaller, last whorl somewhat 

 flattened above. Animal having the jaw of Zonites but the 

 dentition of the Testacellidse. North America. Z. concavus^ 

 Say (xciii, 94). Dr. Fischer has made this group the type of a 

 family Selenitidse, characterized by the peculiarities of jaw and 

 dentition. 



HAPLOTREMA, Anccy, 1881. Shell much smaller, peristome 

 sharp. Z. Duranti^ Newcomb. 



MORCHiA, Albers, 1860. Shell widely umbilicated, depressed 

 orbicular, rather thin, dark-colored, slightly striate, shining ; 

 whorls five ; aperture semioval ; peristome simple, acute ; outer 

 margin flexuous, columellar margin slightly thickened. Z. con- 

 color^ Per. West Indies. 



Nanina, Gray, 1834. 



Distr. — 503 sp. Universal, in tropical and subtropical regions 

 of Asia, Africa and Oceanica. 



Shell heliciform, perforated, dextral or sinistral, somewhat 

 depressed, thin, polished, particularly inferiorly, rounded or 

 carinated at the periphery ; columellar lip short, reflected, often 

 covering the umbilicus ; outer lip simple or scarcely I'eflected. 



Animal with two anterior mantle-lobes covering a part of 

 the surface of the shell; foot long and narrow, posteriorly more 

 or less truncated and glandular, the pore slit-like, sometimes 

 surmounted by a horn-shaped protuberance. The mantle-lobes 

 possess some power of lateral movement, and the faculty of 

 expansion and retraction. 



ariophanta, Desmoulins, 1833. Shell sinistral, umbilicated, 

 thin, diaphanous, the last whorl sometimes angulated or carinated 

 on the periphery. Animal similar to Helix, but having a very 

 large tubercular caudal gland. N. regalis, Chemn. (xciii, 81). 



