262 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 85 



The type, U.S.N.M. no. 468695, has 4 whorls remainmg and meas- 

 ures: Length, 23.1 mm; greater diameter, 16.2 mm; lesser diameter, 

 11.4 mm. 



Figure 8(. — Distribution of the subspecies of Chondrothyra {Chondrothyra) atristoma: 

 (1) umhrata; (2) luctifera; (3) atristoma. 



CHONDROTHYRA (CHONDROTHYRA) ATRISTOMA ATRISTOMA, new subspecies 



Plate 16, Figure 1 



Shell broadly ovate, the first fraction of the first whorl white, the 

 rest of the nuclear turns and the three first postnuclear turns dark 

 blackish brown. The remaining postnuclear whorls dark horn-brown, 

 frequently with an interrupted zone of spots near the summit and on 

 the base. The broadly expanded peristome and the outer edge of the 

 inside of the peristome purplish, blackish brown, except for a little 

 spot on the parietal wall near the posterior angle, which is paler. 

 The sculpture is that characteristic of the species. 



This race comes from the Abra de Bejarano, Mogote El Canalete. 



The type, U.S.N.M. no. 468693, a perfect specimen, has 7.1 whorls 

 and measures: Length, 27.8 mm; greater diameter, 16.9 mm; lesser 

 diameter, 11.8 mm. 



CHONDROTHYRA (CHONDROTHYRA) ATRISTOMA LUCTIFERA, new subspecies 

 Plate 16, Figure 2 



In this subspecies the tip of the shell is dark and so is the peristome, 

 while the rest of the shell is white or pale yellowish, giving it a de- 

 cidedly mourning effect. The sculpture is that t^-pical of the species. 



