CUBAX SUBFAMILY CHONDROPOMINAE TORRE AND BARTSCH 341 



isimple, sliglitly expanded and reflected, that of the parietal wall 

 usually free. Operculum thin, paucispiral, with the nucleus almost 

 submarginal, the outside covered with a thin deposit of fine cal- 

 careous granules. 



The type, U.S.N.M. no. 11008, was collected by C. Wright in the 

 jurisdiction of Colon. It has a little over 4 whorls and measures: 

 Length, 10.9 nun; greater diameter, 11.1 mm; lesser diameter, 8.7 

 mm. 



The specimens before us show great diversity in size, and it is most 

 jjrobable that the smaller ones represent the males. This species, 

 which at first sight suggests C. {C.) picfum by its general form and 

 •simple peristome, is nevertheless so widely separated from it that 

 we do not hesitate to give it specific rank. The much stronger axial 

 sculpture, the narrow channeled suture, and the numerous fine denti- 

 cles at the summit easily separate it from the pictimi group. 



CHONDROPOMA (CHONDROPOMA) VESPERTINUM Morelet 



Shell elongate-conic. The ground color may be flesh-color or pale 

 liorn-color. or pale brown, or with purplish tinge. In addition to 

 this, there are interrupted spiral bands of brown both on spire and 

 base, of varying width, intensity, and spacing. The axial riblets 

 are usually a little stronger at the summit, where they terminate 

 as slender white denticles. The inside of the umbilical wall is of a 

 brownish purple, interior of aperture varying with the intensity of 

 the coloration on the outside, but at all times showing the spiral 

 bands where present on the inside of the outer lip. Peristome almost 

 white. The plug at the truncated end usually shines through the 

 substance of the shell as a dark oblique band. Nuclear whorls 2, 

 inflated, well rounded, smooth, except the last portion of the last 

 whorl, which shows the fine beginning of the postnuclear sculpture, 

 forming an almost flattened apex, narrowly shouldered at the sum- 

 mit. Postnuclear whorls marked by feeble, threadlike, retractively 

 slanting, rather closely spaced, axial riblets, which are strongest at 

 the summit which they render finely denticulate. In addition to this, 

 the whorls are marked by slender, low, rounded spiral threads, which 

 are considerably stronger than the axial riblets. These two elements 

 give to the shell a finely fenestrated aspect. Suture rendered rather 

 constricted by the slight shoulder at the summit. Periphery strongly 

 rounded. Base well rounded, openly umbilicate, marked by the con- 

 tinuation of the axial riblets and spiral threads, which are as strong 

 as those on the spire. Within the umbilicus, however, the spiral 

 threads become finer and a little more closely spaced. Last whorl 

 solute for about one-tenth of a turn. Aperture oval, posterior angle 

 rather acute; peristome simple, slightly expanded, and slightly re- 

 flected. Operculum thin, paucispiral, with almost submarginal nu- 



