No. 2327. THE ANNULABIIDAE— HENDERSON AND BARTSCH. 71 



Cydostoma monstrosa C. B. Adams Jamaica. 



Cyclostoma pearmanaeanum Chitty Jamaica. 



Cydostoma simillima Vendryes Jamaica. 



Adamsiella jarvisi Henderson Jamaica. 



Cydostoma miranda C. B. Adams Jamaica. 



ADAMSIELLOPS, new subgenus. 



Shell ranging from ovate-conic to elongate-conic in form. Axial 

 sculpture stronger than the spiral, the latter imparting an articulated 

 appearance to the ribs. Operculum typically Adamsielloid. 

 Type of the subgenus.— Cyclostoma ignilahre C. B, Adams. 

 The following species are now referred to this subgenus. They fall 

 into two groups as follows : 



The group of Adamsiellops antiguense : 



Choanopoma occidentale Pfeiffer Lesser Antilles. 



Cydostoma antiguense Shuttleworth Lesser Antilles. 



Cydostoma lugubris Pfeiffer Lesser Antilles. 



The group of Adamsiellops ignilahre : 

 Cydostpma ignilahre C. B. Adams Jamaica. 



Annularinae, new subfamily. 



Shell ranging in form from helicoid to elongate-conic. The axial 

 sculpture may be almost obsolete or it may consist of strong ribs or 

 many slender lamellae which may or may not be gathered into tufts 

 at the summit. The spiral sculpture may be absent, confined to the 

 umbilicus, or cover spire and base. In strength the spiral sculpture 

 varies from fine threads to strong cords. Breathing devices are 

 present in some groups and absent in others. They range from a 

 mere notch or slit puncture to a pore with external siphon. The 

 operculum may be flat or convex on the outside, provided with 

 strong calcified lamellae, which rise from the inner edge of the whorls. 

 These lamellae may be vertically placed upon the basal plate or they 

 may be obliquely situated or reflected to parallel the basal plate. 

 They may be almost smooth or ribbed. 



Type genus. — Annularia Schumacher. 



Genus ANNULARIA Schumacher. 



1817. Annularia Schumacher, Nouv. Syst. Hab. Vers Test., pp. 60 and 196. 

 Shell ranging in form from turbinate to elongate-conic. The 

 sculpture may consist of axial riblets only, or of axial riblets and 

 spiral threads. The latter may be confined to the lunbflicus or may 

 be present on the entire shell. There is a great range of variation 

 in the strength of these sculptural features in difl^erent species. 

 Breathing devices may be present o^ absent. The operculum con- 

 sists of a chondroid plate, composed of a number of whorls which 



