254 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 85 



color, axially or spirally banded or both. Peristome broadly ex- 

 panded in one plane, not cut on the inner lip, radiatingly fluted, 

 marked by concentric lines of growth. Breathing pore present on 

 the parietal wall, near the posterior angle of the aperture a little 

 behind its edge. Operculum thin, usually covered more or less with 

 a fine granular calcareous deposit. 

 Tyg^: Chondropoma egregia (Gundlach) Pfeiffer. 



KEY TO THE SPECIES OF SUBGENUS CHONDROTHYRA 



Peristome white or yellowish. 

 Shell stout. 



Greater diameter more than 17 mm rutila 



Greater diameter less than 17 mm egregia 



Shell not stout. 



General color chestnut-brown subegreg-ia 



General color not chestnut-brown. 



General color various, but not brown testa 



Peristome not white or yellowish. 



Peristome blackish brown atristoma 



CHONDROTHYRA (CHONDROTHYRA) RUTILA, new species 



Shell large, elongate-ovate, with the whorls rather gibbous, with 

 the apex and peristome white; the latter with or without dark radi- 

 ating rays and axial band behind the peristome. The rest of the 

 shell may be plain brilliant orange or clouded with dark axial zones, 

 as well as spiral markings. Aperture large, broadly oval ; peristome 

 double, the outer broadly expanded, radiatingly fluted and marked 

 with concentric laminae, the inner moderately expanded and ex- 

 serted and adnate to the outer. Operculum thin, corneous, covered 

 with a thick deposit of calcareous granules, which are heaviest on the 

 inner margin and become less dense outwardly, disappearing before 

 reaching the edge. 



This species occupies the Mogote El Queque and the little mogote 

 of Martin Miranda. 



This differs from the red forms of Chondrothyra {Chondrothyra) 

 tosta in having the sculpture finer. 



KEY TO THE SUBSPECIES OF CHONDROTHYRA (CHONDROTHYRA) RUTILA 



Shell unicolor rutila 



Shell clouded nebulosa. 



CHONDROTHYRA (CHONDROTHYRA) RUTILA RUTILA, new subspecies 



Plate 17, Figure 3 



Shell brilliant orange with a more or less strongly developed dark 

 axial zone behind the peristome. The back of the peristome with. 



