No. 2327. THE ANNULARIIDAE— HENDERSON AND BARTSCH. 63 



axial ribs and spiral threads. All, even those without spiral sculpture 

 on the spire and base, have spiral threads on the umbilical wall. A 

 special breathing device is present in all members of this genus. 

 This may consist of a pore connected with the outer edge of the peri- 

 stome, as in the subgenus ChondrotJiyrium, or of a puncture without 

 slit, as in the subgenera Chondrothyroma, Chondrofloyra, and Chondro- 

 thyretes. The operculum is simple; that is, it consists of a chondroid 

 plate made up of a varying number of whorls, the outer thin edges of 

 which are sometimes faintly upturned to form a suggestion of an obso- 

 lete lamella. The outer surface of the operculum has a deposit of 

 calcareous granules, which is usualh' very slight, but in some species 

 rather pronounced. 



Type of (lie genus. — Cyclostoma egregium (Gundlach) PfeifFer. 



CHONDROTHYRIUM, new subgenus. 



Shell of ovate-conic form marked by axial and spiral threads. 

 Breathing pore present in the parietal wall, connected with the outer 

 edge of the peristome by a slit. Operculum typically Chondropo- 

 moid. 



Tyjje of the subgenus. — Cyclostoma violaceum Pfeifi'er. 



The following species are now referred to this subgenus : 



Cyclostoma violaceum Pfeiffer Central Cuba. 



Cyclostoma crenimargo Pfeiffer Central Cuba. 



CHONDROTHYROMA, new subgenus. 



Shell turbinate, openly umbilicated, marked by axial ribs only, 

 excepting the umbilical wall, which shows strong spiral threads. The 

 breathing pore is on the parietal wall, a little behind the broadly ex- 

 panded peristome, close to the posterior angle of the aperture. Oper- 

 culum tj'pically Chondropomoid with subcentral nucleus. 



Tyjje of the subgenus. — Cyclostoma sagehieni Poey. 



The type species is the onlj^ one known of this group at present. It 

 comes from western Cuba. 



CHONDROTHYRA, new subgenus. 



Shell varying from ovate-conic to elongate-conic, marked by axial 

 and spiral threads. Peristome broadly expanded in one plane; that 

 is, not notched or inbent at the umbilicus. The breathmg pore per- 

 forates the parietal wall a little behind the peristome and a little 

 anterior to the posterior angle of the aperture. Operculum typically 

 Chondropomoid. 



Type of tlie subgenus. — Cyclostoma egregium (Gundlach) Poey. 



The following species are now referred to this subgenus. They 

 fall into two groups as follows: 



The group of Chondrothyra egregium: 



Cyclostoma egregium (Gundlach) Poey Western Cuba. 



{Licina percrassa (Wright) Pfeiffer) W^estern Cuba. 



