PLEURODONTE. 93 



The strong, opaque, carinated shell, with toothless aperture, uni- 

 colored or with few, broad bands, is characteristic, as is also the very 

 long epiphallus and short flagellum, and the blunt, broad cusps of 

 the teeth. The jaw is either smooth or ribbed, as in Caprinm. 

 A fuller knowledge of the genitalia is necessary for the final _settle- 

 ment of specific limits; meantime the following arrangement is 

 offered. 



P. caracolla Linn., v, 120. sagemon Beck. 



tornata Born. arangiana Poey. 



albilabris Lam. marginatoides d'Orb. 



ocnlatus Montf. f fasciata Blv. 



P. excellens Pfr., v, 120. f indiscreta Beck. 



P. insititia Shutt., v, 121. v. gutierrezi Poey, v, 125. 



P. sarcocheila Morch, v, 121. v. schwartziana Pfr., v, 125. 



P. angistoma Fer. v. mina Pfr., v, 12,5. 



angystoma Dh. , marginata Orb. 



anchistoma v. Mart. jactata Gundl. 



P. bornii Pfr., v, 127. v. rostrata Pfr., v, 126. 



marginella Pfr not Gmel. pazensis Poey. 



P. bizonalis Desh., v, 127. cupulata Pfr. 



v. gaskoini Pfr. v, 127. v. marginelloides d'Orb., v, 126. 



P. marginella Gmel., v, 124. transitoria Pfr. 



marginata Born. v. semiaperta v. Mart., v, 125. 



Section Isomeria Albers, 1850. 



Isomeria ALB., Die Hel., p. 126, type H. oreas Koch. v. MART., 

 Die Hel., p. 155. PILSBRY, Manual of Conch, v, p. 135. 



Shell depressed, solid, opaque, chestnut or chocolate colored, rounded 

 or obtusely carinated at the periphery, im perforate or umbilicated. 

 Spire depressed, convex, with 6 or fewer whorls, the last deflexed or 

 straight in front. Aperture wider than high, very oblique ; peristome 

 expanded or reflexed, toothless or with small teeth, of which one is 

 situated near the termination of the periphery; ends of peristome 

 remote, joined by a parietal callus, the parietal wall often having 

 an oblique tooth. Type P. oreas Koch. (pi. 25, figs. 2, 3, P. faunus 

 var. ritchieana). 



Animal unknown. 



A group of large and beautiful dark colored helices confined to 

 the valleys of the higher Andes of Ecuador and Columbia, where 



