CUBAN^ SUBFAMILY CHONDROPOMIXAE — TORRE AND BARTSCH 195 



duced to iiicrenieiital lines. There is also a wide range of strength in 

 the development of the spiral sculpture, which may be confined to the 

 umbilicus or may cover the entire shell. Breathing devices are present 

 in some groups and absent in others. The chief character of the sub- 

 family, however, is found in the operculum, which consists of a thin, 

 simple chondroid basal plate of several whorls, the outer edge of which 

 may be faintly upturned to form a very fragile, low, slender lamella, 

 suggesting the starting point of the subfamily Adamsiellinae. This is, 

 however, usually soon brushed away, leaving the operculum as a plain 

 plate. The operculum has a deposit of fine calcareous granules which 

 may be very slight or fairly strong, depending upon the species in 

 question. 



Tyfe genius. — Chondropoma Pfeiffer. 



ARTIFICIAL KEY TO GENERA AND SUBGENERA OF SUBFAMILY CHONDROPOMINAE 



Breathing device absent. 



Shell turbinate Chondropometes (p. 196) 



Shell not turbinate. 



Shell turreted Turripoma (p. 251) 



Shell not turreted. 



Shell elongate-conic Hendersonida (p. 234) 



Shell not elongate-conic. 



Shell very broadly ovate Orientipoma (p. 390) 



Shell not very broadly ovate. 

 Shell ovate. 



Junctions of axial ribs and spiral threads forming short cusps. 

 Axial ribs gathered into tufts at the summit. Scobinapoma (p. 237) 

 Axial ribs not gathered into tufts at the summit. 



Outer peristome broadly expanded- Chondropomartes (p. 383) 

 Outer peristome not broadly ex- 

 panded Chondropomisca (p. 375) 



Junctions of axial ribs and spiral threads not forming short cusps. 

 Axial ribs gathered into tufts at the summit. 

 Axial ribs threadlike; sculpture re- 

 ticulated Chondropom.orus (p. 363) 



Axial ribs sublamellar; sculpture 



vertebrated Chondropomodes (p. 361) 



Axial ribs not gathered into tufts at the 



summit Chondropoma (p. 322) 



Breathing device present. 



Breathing device a slit in the parietal wall Chondrothyrium (p. 395) 



Breathing device not a slit but a puncture. 



Shell turbinate Chondrothyroma (p. 212) 



Shell not turbinate. 

 Shell turreted. 

 Umbilicus open. 



Shell brightly colored Hendersonina (p. 233) 



Shell not brightly colored Turrithyra (p. 240) 



Umbilicus closed Turrithyretes (p. 240) 



