HISPANIOLAN AND BAHAMAN ANNULARITOAE 185 



divisions of the family but follows, nevertheless, distinct lines of pro- 

 gression from a simple type to a very complicated structure, the steps 

 from one extreme to the other being easily traceable. All the opercula 

 possess a basal chondroid plate upon which calcareous ribs and lamellae 

 are placed, the modifications of which are used in subdividing the family 

 into a series of subfamilies and genera, as will be set forth below. 

 Breathing devices, slits, punctures, and siphons may be present or absent. 



The shell varies in shape from depressed-helicoid to elongate-conic. 

 The sculpture varies from smooth to axially ribbed and spirally lirate, 

 the intensity of these sculptural elements varying from obsolete to 

 lamellose. 



Type genus: Anmdaria Schumacher. 



The Annulariidae differ from the Pomatiasidae, an Old World group, 

 in the radula. The Pomatiasidae possess multicuspid rachidian, lateral, 

 and inner marginal teeth. The outer marginal is pectinated, but the 

 pectinations are confined to the reflected portion of the tooth. In the 

 Annulariidae, on the other hand, the rachidian and lateral teeth are uni- 

 cuspid, with a few exceptions where a small lateral denticle is present, 

 the inner marginal is multicuspid, and the outer marginal is pectinate, 

 but the pectinations extend beyond the reflected portion, involving the 

 main blade. 



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 Great Antilles. 



The relationship of the Bahaman Annulariidae to Cuba and Haiti may 



be expressed as follows: 



Levipoma Bahama 



Chondrops Bahama 



Chondropomorus Bahama, Cuba, Haiti 



Chondropomisca Bahama, Cuba 



Chondropoma Bahama, Cuba, Haiti 



Opisthosiphona Bahama, Cuba, Isle of Pines 



Opisthosiphon Bahama, Cuba 



Leptopisthosiphon Bahama 



Colonina Bahama, Haiti 



Colonella Bahama 



KEY TO THE SUBFAMILIES FOUND IN THE BAHAMAS 



Operculum a simple chondroid plate Chondropominae 



Operculum not a simple chondroid plate. 



Operculum with riblike reenforcements Rhytidopominae 



Operculum bearing a calicified spiral lamella Annulariinae 



Subfamily Chondropominae Henderson and Bartsch 



1920. Chondropominae Henderson and Bartsch, Prod. U. S. Nat. Mus., vol. 58, 

 p. 59. 

 Annulariid moUusks whose shell ranges in form from turbinate to 



