76 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 58. 



Cistula cumulata Pfeiffer Eastern Cuba. 



Cyclostoina alatum Pfeiffer Eastern Cuba. 



Cyclostoma decoloratum Gundlach Western Cuba. 



The group of Tudorellata auricomum: 



Choanopoma auricomum (Gundlach) Pfeiffer Eastern Cuba. 



Choanopoma putre (Gundlach) Pfeiffer Eastern Cuba. 



Subgenus COLOBOSTYLUS Crosse and Fischer. 

 1888. Colobostylus Crosse and Fischer, Journ. Conchyl., vol. 36, p. 229. 



Shell ranging from elongate-ovate to elongate-conic. Axial ribs 

 present, spiral sculpture absent. Operculum typically Tudoroid. 



Type of the subgenus. — Cyclostoma jayanum C. B. Adams, selected 

 by Dall, 1905. 



The following species are now referred to this subgenus. 



Cyclostoma jayanum, C. B. Adams Jamaica. 



Cyclostoma jayanum, rufilahre C. B. Adams .__Jamaica. 



Cyclostoina jayanum nigrolabre 0, B. Adams Jamaica. 



Cyclostoma humphreysiana Pfeiffer Jamaica. 



Cyclostoma chcvalieA C. B. Adams Jamaica, 



Cyclostoma chevalieri virgatum C. B. Adams Jamaica. 



Cyclostoma chevalieri pulchrius C. B. Adams Jamaica, 



Cyclostoma thysanoraphe Sowerby Jamaica. 



TUDORISCA, new subgenus. 



Shell ranging from elongate-ovate to elongate-conic. Axial ribs 

 present. Spiral sculpture confined to the umbilicus. Operculum 

 typically Tudoroid. 



Type of the subgenus. — Cyclostoma alhus Sowerby. 



The following species are now referred to this subgenus. They 

 fall into two groups as follows : 



The group of Tudorisca alius: 



Cyclostoma alhus Sowerby Jamaica. 



Cyclostoma alhus fuscus C. B. Adams Jamaica. 



Cyclostoma tectilabris C. B. Adams Jamaica. 



Cyclostoma bronni C. B. Adams Jamaica. 



Cyclostoma lamellosum C. B. Adams Jamaica. 



Colobostylus nelsoni Clapp Swan Island. 



Cyclostoma interruptum Lamarck Jamaica. 



The group of Tudorisca cMapensis: 



Adamsiella aripensis Guppy Trinidad. 



Choanopoma chiapensis Crosse Mexico. 



Cyclostoma tamsiana Pfeiffer Venezuela. 



Cyclostomas rectus (Gundlach) Pfeiffer Central Cuba. 



Cyclostoma crenulosus C. B. Adams Jamaica. 



Subgenus TUDORA Gray. 

 1850. Tudora Gray, Brit. Mus. Cat. Cycloph., p. 48. 

 Shell ranging in form from ovate-conic to elongate-conic, marked 

 by axial ribs and spiral threads on spire and base, the former never 



