MUSEUM OF COMPARATIVE ZOOLOGY. 99 



reflected anteriorly in the adult. Max. Ion. of shell, 13.6; of last whorl, 8.0 ; 

 max. lat. of shell, 5.0 mm. 



Habitat. Stations 272 and 273, at Barbados, in 76-103 fms., over a bottom 

 of coral and broken shells, bottom temperature 59° to 65° F. 



This shell, owing to the coarseness of its sculpture, has a somewhat rude 

 appearance, and is very characteristic. Except for the plaits on the pillar, it 

 recalls Pleurotoma (Drillia) pagoda, Reeve. 



Genus MANGILTA (Leach) Risso. 



This genus is used in a manner which includes all the Pleurotomidce with- 

 out opercula, as adopted by Dr. Paul Fischer; though this, of course, is a 

 much wider sense than that in which it was originally employed. Cythara 

 Schumacher is an older name, but it was applied to a particularly modified 

 species and will better be retained with its original limits. For the purposes 

 of this paper the following groups have been admitted: — 

 Subgenus Aforia Dall. 



Shell large, strong, fusiform ; anal notch large, away from the suture. 

 Type, Pleurotoma circinata Dall (insignis Jeffreys), Bering Strait and 

 Aleutian Islands. 

 Subgenus Cythara Schumacher (C. striata Schum.). 

 Subgenus Daphnella Hinds. 



Section Daphnella s. s. (D. lymnceiformis Kiener). 

 Section Eubela Dall (D. limacina Dall). 

 Subgenus G-lyphostoma Gabb (G. dentifera Gabb). 

 Subgenus Mangilia Risso s. s. (M. costulata Risso). 

 Subgenus Pleurotomella Verrill (P. Packardi Verrill). 



1 Section Gxjmnobela Verrill {G. curta Verrill). 

 Subgenus Taranis Jeffreys (T. Mbrchii Malm). 



Subgenus AFORIA Dall. 



This group has the shell of a typical Pleurotoma, but has no operculum; the 

 typical species reaches three or four inches in length, is strongly carinated above 

 the periphery, and the wide rather deep anal sulcus is nearer to the carina 

 than to the suture. The following species is only provisionally referred to 

 this group, as the soft parts are unknown. 



? Aforia hypomela Dall. 



Shell thin, white, fusiform, with a very thin straw-colored epidermis ; nu- 

 cleus white, vitreous, of one and a half turns, polished, nearly smooth with 

 faint spiral lines and lines of growth ; subsequent whorls seven, spirally sculp- 

 tured with (1) a moderate angulation just behind the periphery of the last whorl, 

 which becomes sharper and peripheral on the earlier whorls ; in front of this 

 the whorls are ornamented with numerous rounded threads, separated by much 



