No. 2327. THE ANNULARIIDAE— HENDERSON AND BARTSCH. 55 



vol. 1, p. 75, pi. 5, fig. 1) in describing and figuring a New World 

 species, Cistula cawlcana d'Orbigny, or sometimes believed to have 

 been Cistula illusiris Poey, with a radula possessing a multicuspid 

 rachidian and lateral tooth, or in other words, a typical Old World 

 Erycid radula. The uniformly high order of Troschel's work caused 

 this unfortunate error to be generally accepted without verifications; 

 hence authors have hesitated to separate the American from the Old 

 World forms, believing that the radular differences in the American 

 forms showed a range of variation embracing the characteristics of 

 the Old World group and those of the family now defined. We have 

 examined the radula of both Cistula candeana and of Cistula. illustris 

 and have found them to be typically Annularid. An examination 

 of the radula of many species, includmg all the groups discussed in 

 this paper, has shown no variation in the Annularid characters; 

 that is, unicuspid rachidian and lateral teeth, though minor variations 

 do exist in the marginals. 



The geographic range of the Annulariidae extends from the 

 Bahamas and lower Florida on the north, throughout the Greater 

 and Lesser Antilles, and on the mainland from Mexico to Bolivia. By 

 far the greatest development is centered in the Greater Antilles. 



KEY TO THE SUBFAMILY, GENERA, SUBGENERA, AND GROUPS OF THE FAMILY 

 ANNULARIIDAE. 



A^ Lamellae absent or obsolete on the operculum. 



B'. Basal plate without ribletlike reenforcement Subfamily Chondropominae. 



C^ Breathing slit or pore absent Genus Chondropovia . 



D^ Spiral sculpture confined to the umbilicus. 



E'. Shell turbinate Subgenus Chondropomatus . 



W. Shell not turbinate Subgenus Chondropomium . 



F^ Shell ovate-conic. 



G^ Axial riblets low-rounded Group weinlandi. 



G^. Axial riblets sublamellar Group ambiguum. 



F^. Shell not ovate-conic. 



Shell elongate-conic Group lindenianum. 



D^. Spiral sculpture not confined to the umbilicus. 



E^ Shell turbinate Subgenus Chondropometes. 



E-. Shell not turbinate. 



F'. Intersections of axial and spiral threads forming sharp cusps 



Subgenus Chondropomartes. 

 F^. Intersections of axial and spiral threads not forming sharp cusps. 



G^ Axial riblets developed into tufts at the summit 



Subgenus Chondropomorus. 



B.K Axial riblets not rendered articulate by the spiral sculpture 



Group dentatum. 



W. Axial riblets rendered articulate by the spiral sculpture 



Group saniacruzense. 



G^ Axial riblets not developed into tufts at the summit 



Subgenus Chondropoma. 



H'. Axial riblets stronger than the spiral sculpture Group ra'yem. 



H^. Axial riblets not stronger than the spiral sculpture. 



