CUBAN SUBFAMILY CHOXDROPOMIXAE TORRE AND BARTSCH 261 



CHONDROTHYRA (CHONDROTHYRA) ATRISTOMA, new species 



Shell elongate-ovate, with the tip and peristome blackish brown, 

 the rest of the shell varying in the different subspecies from white 

 through pale brown to dark brown. Interrupted spiral bands and 

 axial streaks may or may not be present in some of the subspecies. 

 Nuclear whorls almost 2, small, Mell rounded, smooth except for micro- 

 scopic granulations. Postnuclear whorls moderately inflated, well 

 rounded, marked by retractively curved, slender, rather closely spaced, 

 axial threads and spiral threads a little stronger than the axial. The 

 junction of the two form minute nodules, while the spaces enclosed 

 between them are more or less rectangular pits. The axial riblets 

 become reduced on the last whorl. Suture moderately constricted 

 with scarcely any indication of crenulations at the summit of the 

 whorls. Periphery and base inflated and strongly rounded, the latter 

 openly umbilicated and marked by the same type of sculpture that 

 characterizes the spire. Aperture very broadly oval, slightly angu- 

 lated posteriorly. Peristome double, the outer broadly expanded with 

 a slight tendency to the formation of a channel at the umbilical region, 

 which the broadly expanded peristome partly covers. The outer peri- 

 stome is radially fluted and marked by concentric laminae. The inner 

 peristome is slightly exserted and slightly reflected. Operculum 

 thin with excentric nucleus covered with a rather heavy finely granu- 

 lose deposit on the inner three-fourths of the turns. 



This species appears peculiar to the Sierra San Andres and the 

 mogotes to the south of it. 



We know at the present time three markedly distinct races, which 

 the following key will help to differentiate : 



Distribution of the subspecies of G. {C.) atristoma is shown in 

 figure 87. 



KEY TO THE SUBSPECIES OF CHONDROTHYRA (CHONDROTHYRA) ATRISTOMA 



Shell, except tip and peristome, chestnut-brown umbrata 



Shell, except tip and peristome, horn-color atristoma 



Shell, except tip and peristome, white luctifera 



CHONDROTHYRA (CHONDROTHYRA) ATRISTOMA UMBRATA, new subspecies 

 Plate 16, Figltje 3 



The early remaining postnuclear whorls dark blackish brown, which 

 gradually changes to chestnut-brown on the later turns. The peri- 

 tome is dark blackish brown, with a little paler spot on the parietal 

 wall near the posterior angle. The sculpture is that of the species, 

 but the lamellae on the outer peristome are particularly strong here. 



This race comes from Pico Grande, Sierra San Andres. 



