296 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 85 



CHONDROTHYKETES INCRASSATA SUBINCRASSATA, new subspecies 

 Plate 22. Fiqitre 9 



This race we have from the Sierra Quemada south of the range 

 of the typical C. incrasHata incras^ata., and from the Mogote Caoba 

 near this. It has the shell thinner and considerably more strongly 

 sculptured than the typical form. 



The type, U.S.N.M. no. 468945, comes from the Sierra Quemada. 

 It has 5.5 whorls remaining and measures : Length, 30.3 mm ; greater 

 diameter, 19.4 mm ; lesser diameter, 14.4 mm. 



CHONDROTHYRETES CERINA, new species 



Shell broadly ovate, wax yellow, sometimes pale orange or chest- 

 nut-brown, or even purplish, unicolor, or marked with axial streaks 

 of a darker shade. Nuclear whorls 2, the first smooth, the second 

 showing the beginning of the postnuclear sculpture at its termina- 

 tion. Postnuclear whorls inflated, strongly rounded, marked on the 

 early turns by retractively slanting axial riblets and spiral threads 

 of almost the same strength; on the later turns these become less 

 conspicuous and in one of the races quite obsolete on the last whorl. 

 The base is short, strongly rounded, and sculptured like the posterior 

 portion of the last turn. Apertuie broadly ovate ; peristome double, 

 the inner reflected over the outer and adnate to it; the outer is 

 moderately, strongly expanded and considerably thickened ; the inner 

 lip is reflected over anterior to the cut, and covers the umbilicus. 

 It is not distinctly angulated as in some of the other species; on the 

 parietal wall it extends over the preceding turn. The outer peri- 

 stome does not project as a conspicuous auricle at the posterior angle. 

 Breathing pore on the parietal wall a little anterior to the posterior 

 angle of the aperture and a little within the peristome. Operculum 

 with almost submarginal nucleus and a considerably thickened cal- 

 careous deposit on the last turn. 



This species occupies the region between Vinales and the Sierra 

 del Infierno, extending southwest to Santo Tomas, Hoyo del Guama, 

 and to the Ensenada Pan de Azucar, and across the Sierra Martillo, 

 breaking up into a number of subspecies, which are here described. 



The shells of this species can readily be distinguished from its 

 nearest relative, C. incrassata (Wright), by having the auricle at 

 the posterior angle of the aperture almost absent and by having 

 the outer peristome of the inner lip anterior to the notch not ex- 

 panded, but forming an almost straight thickened columella, while in 

 incrassata it always projects as a sharp element. C. incrassata also 

 has the inner peristome much more thickened and much broader. 



The animal of C. cerina subceiina is short, ashy gray, with the 

 head adjoining the tentacles, a little paler, which is also the case at 



