272 BULLETIN 181, UNITEiD STiATES NATTONiAL MUSEUM 



zuela, on the east side of the bay ; this is across the bay from Trinidad. 

 It has 4.5 whorls and measures : Height, 16.6 min. ; greater diameter, 

 21.2 mm. ; lesser diameter, 15.8 mm. Height of aperture, 10.7 mm. ; 

 diameter, 10.8 mm. 



We are unable to differentiate this from the large series of Trinidad 

 specimens before us and therefore apply Guppy's name to it. It is 

 nearest related to ^. (O.) tranducidvmi hejumense (H. B. Baker) 

 from which the finer sculpture will distinguish it. 



APEROSTOMA (CYCLOHIDALGOA) TRANSLUCIDUM PYGMAEUM, new subspecies 



Plate 30, Figxjees 19-21 



Shell very small, thin, helicoid, strongly elevated, yellowish horn 

 colored. The nucleus consists of 2 well-rounded smooth turns, form- 

 nig a rather high apex. The postnuclear whorls are inflated, strongly 

 rounded, and marked by obsolete, retractively curved axial riblets. 

 Suture strongly impressed. Periphery well rounded. Base moder- 

 ately broadly umbilicated, inflated, strongly rounded, and marked by 

 the continuation of the obsolete sculpture referred to for the spire. 

 Aperture circular, slightly produced into an angle at the posterior 

 angle; peristome simple, the outer and imier lips thin. The parietal 

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

 treme complete. The operculum is typically aperostomid and shows 

 5 whorls. 



The type, U.S.N.M. No. 24026, was collected by F. E. Sumichrast at 

 Caratal, Venezuela. It has 4.2 whorls and measures : Height, 9.9 mm. ; 

 greater diameter, 12.6 mm. ; lesser diameter, 9.3 mm. Height of aper- 

 ture, 5.9 mm. ; diameter, 6.1 mm. 



U.S.N.M. No. 515727 contains five topotypes from the same source. 



The very small size readily distinguishes this form from all the 

 other members of the group. 



APEROSTOMA (CYCLOHIDALGOA) TRANSLUCIDUM TRANSLUCIDUM (Sowerby) 



Plate 30, Fiquees 1-3, 10-12 



1843. Cyclostoma translucidum Soweeby, Proc. Zool. Soc. London, vol. 11, p. 29. 

 1843. Cyclostoma translucidum Sowerby, Thesaurus conchyliorum, vol. 1, p. 106, 



pi. 23, fig. 4. 

 1852. Cijclotus translucidus Pfeiffeb, Monographia pneumonomoporum viventium, 



vol. 1, p. 20. 

 1888. Neocyclotus translucidus Fischer and Crosse, Mission scientiflque au 



Mexique et dans I'Am^rique centrale, vol. 2, pt. 7, p. 162, pi. 48, fig. 1. 

 1923. Poteria (Neocyclotus) transludda translucida H. B. Baker, Occ. Pap., 



Mus. Zool. Univ. Michigan, No. 137, pp. 31, 33. 

 1923. Poteria {Neocyclotus) translucida santaguitensis H. B. Bakee, ibid., pp. 33, 



35, pi. 5, figs. I. J. 



