PLEUROTOMID^. 151 



been recently recliristened Donovania. but it appears unneces- 

 sary to make any change. 



Genus BORSONIA, Bellardi, 1846. 



Shell fusiform, spire elevated ; canal well-marked ; columella 

 with one or two strong plications ; sinus of the outer lip not 

 deep, opening in the infrasutural depression of the body-whorl. 



Abyssal zone, West Indies and Brazil. Fossil, tertiary of 

 Europe and America. 



Described from a fossil group having a single columellar plait, 

 but Cordiera, Rouault ( Scobinella, Conrad), having two 

 plaits, is usually considered identical, as in examples of some 

 species one or two plaits appear to be indifferently developed. 



II. Cla,vatulinse. 

 Genus CLAYATULA, Lamarck, 1801. 



Shell fusiform, with well-produced spire, the whorls coronated 

 with tubercles or short spines at the suture; aperture oval; 

 columellar lip smooth, arcuate, callous behind ; outer lip thin, 

 arcuated, with the sinus situated below the sutural coronal. 

 Operculum semioval, the nucleus about the middle, on the inner 

 side. 



Foot large, short, obtuse behind ; eyes placed externally near 

 the extremity of the tentacles. Dentition : a small unicuspid 

 central tooth with single sharp laterals (1-1-1). 



The species mostly inhabit the west coast of Africa ; they 

 also occur in the tertiary of Europe. 



Subgenus PERRONA, Schumacher, 181 7 (Tomella, 



Swains., 1840). 



Spire carinated or smooth, whorls not tubercular or spinose ; 

 sinus more or less near the suture. 



Subgenus CLIONELLA, Gray, 1847. 



Shell narrowly bucciniform, turriculated, whorls somewhat 

 flattened, longitudinally ribbed, having a thick epidermis ; spire 

 elevated ; canal scarcely indicated at the broad base of the 

 aperture ; lip with a small infrasutural sinus. Operculum with 

 lateral nucleus. 



