No. 2327. TEE ANNVLABIIDAE— HENDERSON AND BARTSCH. 69 



with the ribs not completely covering the whorls, thus showing the 

 basal chondroid plate in a narrow sinus, which marks the outer edge 

 of the turns. Both the inner and outer end of the retractively 

 curved ribs are fused into lamellae, which are considerably higher 

 than the ribs which extend in a gentle curve between them. 

 Type of the genus. — Cyclostoma rugulosum Pfeiffer, 

 The following species are now referred to this genus : 



Cyclostoma rugulosum Pfeiffer Matanzas 



Cyclostoma nodulatum Poey Matanzas. 



Cyclostoma clathratum Gould Matanzas. 



Cienopoma wrightianum (Gundlach) Arango Western Cuba. 



Ctenopoma nodi/erum Arango Cuba. 



Cyclostoma honestum Poey Havana. 



Cyclostoma coronatum Poey Havana. 



TORRELLA, new genus. 



Shell elongate-conic, marked by sublamellar axial riblets only 

 on the spire, or by sublamellar axial riblets and obsolete spiral 

 threads. The umbilicus may be marked by weak or strong spiral 

 cords. Peristome expanded, simple or fimbriated. Breathing siphon 

 almost straight or decidedly flexed and bent into the umbilicus. 

 Operculum with the ribs occupying only a portion of each whorl and 

 as high as the inner and outer lamellae, which are formed by the 

 fusing of the ribs. Dedicated to Dr. Carlos de la Torre. 



Type of the genus. — Ctenopoma torreianum (Gundlach) Arango. 



TORRELLA, new subgenus. 



Shell elongate-conic, marked by slender sublamellar axial ribs 

 and obsolete spiral cords. The latter render the ribs somewhat sin- 

 uous, and slightly foliate at their junctions. Umbilicus marked by 

 strong spiral cords. Peristome expanded and fimbriated at the edge. 

 Breathing siphon strongly flexed and bent into the umbilicus, which 

 it completely closes. Breathing, when the animal is withdrawn, is 

 effected through the hollow axis of the shell. Operculum t}^ical 

 Torrelid. 



Type of the subgenus. — Ctenopoma torreianum (Gundlach) Arango. 



The following species are now referred to this subgenus: 



Ctenopoma torreiana (Gundlach) Arango Havana. 



Cyclostoma defidens Gundlach Matanzas. 



Cyclostoma immersum Gundlach Matanzas. 



TORRELLISCA, new subgenus. 



Shell elongate-conic, marked by slender sublamellar axial riblets 

 only on the sphe. Umbilicus marked by weak spiral cords. Peri- 

 stome expanded but not fimbriated. Breathing siphon a simple 



