THE CYOLOPHORID LAND MOLLUSKS OF AMEHIOA 253 



Type locality : Pozuzo, eastern Peru. 



Da Costa further adds: "There is a certain resemblance between 

 this shell and N. cingulatus, Sowb., from Colombia, but it is less 

 openly umbilicated and not so strongly striated. The different geo- 

 graphical distribution of the two species should be sufficient to dis- 

 tinguish them. The shelly operculum is thick and consists of 8-9 

 whorls, which are thickened at the inner edge," 



The very broad umbilicus will distinguish this from the other 

 members whose last whorl is not finely regularly ribbed. 



APEROSTOMA (APEROSTOMA) SALENGOENSE, new species 



Plate 37, Figxjbes 18-20 



Shell low, helicoid; the denuded early whorls pinkish, the later 

 turns soiled white. Where the periostracum remains this is shown 

 to be golden-yellow on the upper surface. There is a narrow light 

 zone at the periphery and the base has a broad, dark, colored band 

 covering two-fifths of its surface. Anterior to this, including the 

 umbilical wall, the base has a horncolored periostracum; interior of 

 the aperture bluish white. The nucleus consists of 2 small, well- 

 rounded, smooth turns, forming a rather pointed apex. The post- 

 nuclear whorls are well rounded, with a slightly impressed area 

 a little below the suture on the last turn and a weak cord at the sum- 

 mit, which is appressed to the preceding turn. The postnuclear 

 whorls are marked by rather irregular, poorly developed, retrac- 

 tively slanting axial riblets which become evanescent on the last part 

 of the last turn. Suture strongly impressed. Periphery feebly an- 

 gulated. Base moderately openly umbilicated, inflated, well-rounded, 

 and marked by the same type of sculpture as that which characterizes 

 the upper surface. Aperture broadly oval with a slight auricle at the 

 posterior angle ; peristome simple ; the outer lip produced at its junc- 

 tion with the basal lip and slightly reflected, thin ; the inner slightly 

 thickened. The parietal wall is covered by a thick callus, which is 

 separated from the preceding turn by an impressed groove, which 

 renders the peritreme complete. 



The type, U.S.N.M. No. 104432, was collected by Cuming at Salengo 

 Island, Ecuador. It has 4.6 whorls and measures : Height, 21.5 nun. ; 

 greater diameter, 37.4 mm.; lesser diameter, 25.4 mm. Height of 

 aperture, 13.5 mm. ; diameter, 17.7 mm. 



The appressed summit distinguishes this species from the other 

 members of the group having a moderately broad umbilicus. 



428349—42 17 



