18 BULLETIN 192, UNITED STATES NATIONAL MUSEUM 



outer half of the parietal wall of the open umbilicus. The last whorl is 

 slightly solute. Aperture broadly oval ; peristome simple, but with an in- 

 dication of doubling at the posterior angle. This probably is occasioned 

 by a tuft. The inner lip, too, has a slight indication of doubling. 



The type (U.S.N.M. No. 493320) was collected by John B. Hender- 

 son at San Marc, Haiti. It has 4.5 whorls and measures: Length, 

 15 mm.; greater diameter, 8.9 mm.; lesser diameter, 7 mm. 



CHONDBOPOMA (CHONDBOFOMOBUS) PETITIANUM (Pfeiffer) 



Shell elongate-conic, of flesh or pale brown ground color, variously 

 mottled, streaked, spotted, or interruptedly spirally banded with brown; 

 the inside of the aperture varies from flesh color through horn color, 

 through pale brown, showing brown rays on the outer lip of both 

 peristomes. The posterior fourth of the first nuclear whorl is very dark 

 chestnut-brown, the rest horn-colored. Nuclear whorls 2 or a little 

 more, strongly rounded, forming a truncated apex, the last portion of 

 the last nuclear turn being marked by fine lines of growth. The post- 

 nuclear whorls are well rounded and marked by slender axial ribs, 

 which may be closely or rather distantly spaced, depending upon the 

 subspecies in question; but no matter which, some of them are always 

 gathered into rather distantly spaced tufts at the summit. In addition 

 to the axial sculpture, the whorls are marked by spiral threads, which 

 may be as strong as the axial riblets or a little weaker. Their junction 

 with the axial ribs usually produces fine nodules, while the spaces en- 

 closed between them vary in the various subspecies from rectangular 

 to squarish pits. The suture is moderately constricted. Periphery ob- 

 soletely angulated. The base is moderately long, narrowly openly um- 

 biUcated, well rounded, and marked by the continuation of the axial ribs 

 and spiral threads, the latter about as strong as those on the spire; 

 those near the umbilicus, however, are usually a little heavier. Aperture 

 very broadly oval ; peristome double, the outer moderately expanded on 

 the outer and basal lips, the inner projecting slightly above the outer and 

 only moderately expanded. Operculum paucispiral with the nucleus half- 

 way between subcentral and marginal. 



The material before me shows that this species is distributed over 

 northern and central Haiti and the Dominican Republic. The following 

 key will help to distinguish the subspecies composing it: 



KEY TO THE SUBSPECIES OF CHONDROPOMA (CHONDROPOMORUS) 



PETITIA>fUM 



Axial ribs distantly spaced costatum 



Axial ribs not distantly spaced. 



Intercostal spaces wider than axial ribs. 



Umbilicus rather broad dominicum 



Umbilicus narrow. 



Axial ribs on last whorl about 80 dessalinesi 



Axial ribs on last whorl about 110 hispaniolae 



Intercostal spaces not wider than axial ribs petitianum 



