THE CYOLOPHORID LAND M0LLUSK9 OF AMEiRDClA. 239 



APEROSTOMA (APEROSTOMA) MANABENSE, new species 

 Plate 34, Figuees 10-12 



Shell of medium size, very depressed-helicoid. The early denuded 

 whorls pale red, the last covered with a thin, reddish olivaceous, horn- 

 colored periostracum. There is a narrow light zone immediately 

 above the periphery, while the posterior half of the base is chestnut- 

 brown, and the anterior half and umbilical wall are paler than the 

 upper surface; interior of aperture bluish white with a livid tinge. 

 The nucleus consists of 2.4 small, well rounded, smooth turns. The 

 postnuclear whorls are slightly rounded. There is a shallow groove 

 immediately below the summit. The last whorl is obliquely deflected 

 for about four-fifths of a turn. The postnuclear whorls are marked 

 by weak, retractively slanting, very slender, closely spaced axial rib- 

 lets, which become evanescent on the last half of the last turn, where 

 they are represented by mere lines of growth. Suture well impressed. 

 Periphery well rounded. Base broadly, openly umbilicated, inflated, 

 strongly rounded, marked by the continuation of the axial riblets 

 which become fused into stronger ribs on the anterior half of the 

 base and umbilical wall. Aperture decidedly oblique, tear-shaped, 

 drawn out into a decided angle at the posterior angle; peristome 

 thin on the outer and basal lip ; a little thicker on the inner lip. The 

 parietal wall is covered by a thick callus, which renders the peri- 

 treme complete. 



The type, U.S.N.M. No. 524066, was collected by O. Haught be- 

 tween Quevedo and Calcata, Manabi, Ecuador. It has 4.8 whorls 

 and measures: Height, 23.2 mm.; greater diameter, 43 mm.; lesser 

 diameter, 29.4 mm. Height of aperture, 16.5 mm. ; diameter, 20.3 mm. 



The wide umbilication suggests A. (A.) gigantenm (Reeve), from 

 which it is distinguished by its small size. 



APEROSTOMA (APEROSTOMA) FISCHERI (Hidalgo) 



Plate 34, Figures 1-3 



1867. Cyclotus fischeri Hidalgo, Journ. Conchyl., vol. 15, p. 305, pi. 8, fig. 3. 



1901. Aperostoma fischeri Sykes, Journ. Malac, vol. 8, p. 105, pi. 10, fig. 3. 



1912. Neocyclotus giganteus Kobelt (pars), Martini-Chemnitz Conchylien Cabi- 

 net, vol. 1, sect. 19, pt. 3, p. 891, pi. 133, fig. 1. 



1923. Poteria (Neocyclotus) fischeri H. B. Bakee, Occ. Pap. Mus. Stool. Univ. 

 Micliigan, No. 137, p. 42. 



Shell moderately large, helicoid. The early whorls rose-red; the 

 last covered with an olivaceous pale chestnut-colored periostracum. 

 There is a narrow light zone at the periphery, while the posterior half 

 of the base is conspicuously bright chestnut-brown ; the anterior half 

 and the umbilical wall are much paler. The interior of the aperture 

 is bluish white. The nucleus consists of 2 very small, well-rounded 



