98 PLEURODONTE. 



the last often carinated, slightly deflexed in front. Aperture 

 oblique, the peristome thick, expanded, simple or bearing obtuse 

 teeth, and having an obtuse fold near the eolumellar insertion. Type 

 P. imperator, pi. 22, fig. 9. 



Anatomy unknown. Eggs large, oblong, with a hard calcareous 

 shell, that of P. imperator (pi. 22, fig. 10) measuring 8i by 12 mill. 

 Young having when hatched a granulated, umbilicated shell of 

 about 2 whorls, measuring about one-fifth the diameter of the adult 

 shell. 



The shell in this section is generally marked with many spiral 

 lines of brown, the widest and most conspicious being immediately 

 below the periphery. P. apollo is sometimes unicolored. It will be 

 seen that in coloration, the relationship of Polydontes to Parthena 

 (P. dominicensis, etc.) is extremely close. All three species of 

 Polydontes are known to voluntarily amputate their tails when 

 captured (Journ. de Conchyl. 1860, p. 226). They live under dead 

 leaves. Distribution, eastern Cuba. 



P. imperator Montf., v, 79. P. sobrina Fer., v. 80. 



magica Fer. crassilabris Pfr. 



P. apollo Pfr., v, 79. 



Section Parthena Alberp. 

 Parthena ALB., Die Hel., p. 112 (first species If. angulata). 



Shell imperforate, globose or depressed, the periphery rounded or 

 carinated; spire short, whorls 4-4, the earlier 1| forming a gran- 

 ulated or radially grooved embryonic shell, the last notably inflated 

 and capacious, unicolored or begirt with many brown lines ; surface 

 granulated. Aperture large ; peristome expanded ; columella 

 arcuate. Type P. angulata, pi. 22, fig. 2. (See also pi. 22, fig. 3, 

 P. dominicensis). 



Animal (of P. dilatata') having the sole undivided, with no 

 indication of lateral borders or pedal grooves. Upper surface and 

 sides coarsely granulated, the granules arranged in descending rows 

 on the sides, finer and irregular on the back ; tail rounded above ; 

 back from mantle to face irregularly granulated, lacking longitud- 

 inal grooves. Mantle-edge lacking shell-lappets ; body-lappets well 

 developed, the right one short, the left extending the entire length 

 of the outer lip of the shell (pi. 23, fig. 15, showing posterior angle 

 of aperture, respiratory opening and lappets). 



