TRIPIIORIS. 287 



Genus BITTIUM, Leach. 



Operculigerous lobe with rudimentary expansions on 

 each side, and furnished with a roundish, lanceolate 

 cirrhus (Loven). 



Operculum subcircular, of four volutions. 



Shell turreted, many-whorled, granular, often with irre- 

 gular varices ; aperture with a slight canal in front, not 

 produced or recurved ; inner lip simple ; outer lip acute, 

 not reflexed or expanded. 



Ex. B. reticulatum, Da Costa, pi. 30, fig. 3. Oper- 

 culum, B. reticulatum, fig. 3, a. Shell, B. reticulatum, 

 fig. 3, h. 



This genus includes several small northern forms, re- 

 sembling dextral Triphoies, and ranging from low-water 

 to eighty fathoms. 



Species of Bittium. 



elegans, Blainv. neglectum, C. B. Adams. 



gibberulum, C. B. Adams. pulchelhira, C. B. Adams. 



granarium, Kien. reticulatum, Da Costa. 



Greenii, C. B. Adams. scabrum, Oliv. 



iota, C. B. Adams. zebrum, Kien. 



Genus TRIPHORIS, Deshayes. 



Tentacles clavate at the tips, united at their bases by 

 a sinuated veil. 



Operculum orbicular, few-whorled. 



Shell turreted, sinistral; aperture round, produced an- 

 teriorly into a closed, tubular canal, sometimes with a 

 posterior, closed canal. 



