180 BULLETIN 192, UNITED STATES NATIONAL MUSEUM 



U.S.N.M, No, 425515 contains a specimen collected by H. W. Krieger 

 on San Lorenzo Bay. 



These localities are closely approximated. 



This species, while closely related to Incertipoma sanjuanense, which 

 comes from San Juan on the North coast of San Juan Peninsula, can 

 easily be differentiated from it by its much slenderer and smaller size. 



INCERTIPOMA SANJUANENSE, new species 



Plate 30, Figure 1 



Shell elongate-conic, flesh-colored, with a brownish tinge. Nuclear 

 whorls decollated in all our specimens. Postnuclear whorls well rounded, 

 appressed at the summit, and marked by exceedingly fine, hairlike axial 

 riblets, of which 462 are present on the last turn in the type. The spiral 

 sculpture consists of threads a little stronger than the axial ribs. Of 

 these, 32 are present between the summit and the periphery in the type. 

 Suture strongly constricted. Base well rounded, openly umbilicated, and 

 marked by the continuation of the axial riblets, which extend over the 

 umbilical wall, and by 19 spiral threads equaling those on the spire. On 

 the umbilical wall there are other feeble spiral threads a little wider 

 than those on the base. Aperture oval; peristome double, the outer 

 broadly flaringly expanded; the inner moderately exserted and ap- 

 pressed to the outer. Operculum unknown. 



The type (U.S.N.M. No. 425526) was obtained by H. W. Krieger 

 at San Juan on the north coast of the Samana Peninsula, Dominican 

 Republic. It has 5.5 whorls remaining and measures: Height, 19.5 mm.; 

 greater diameter, 10.4 mm.; lesser diameter, 7.8 mm. 



U.S.N.M. No. 425525 contains a topotype. 



This species is distinguished from Incertipoma ncsiotes by its larger 

 and stouter form. 



INCERTIPOMA DOMINICENSE (Pfeififer) 



Plate 30, Figure 7 



1850. Cyclostoma dominiccnse Pfeiifer, Zeitschr. Malak., vol. 7, p. 79. 



1854. Cyclostoma dominicense Pfeiffer, Martini-Chemnitz Conchylien Cabinet, 



vol. 1, sect. 19, pp. 282-283, pi. 38, figs. 9, 10. 

 1891. Ctenopoma dominicense Crosse, Journ. Conchyl., vol. 39, p. 169. 



Shell perforate, elongate, truncated moderately, thick, rendered re- 

 ticulated by raised axial and spiral threads, slightly shining, pale yellow- 

 ish brown. Whorls rather high, very slightly narrower at the summit. 

 Suture regularly denticulated. Whorls remaining 4, moderately rounded, 

 the last slightly solute, keeled at the posterior angle. Aperture parallel 

 with the axis, obliquely angulatedly oval. Peristome double, the inner 

 slightly exserted, the outer somewhat expanded, and broader at the 

 anterior end and at the posterior angle. Length 10 mm. ; diameter 4.8 mm. 



