PLEUROTOMID. 157 
been recently rechristened 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. 
Il. Clavatuline. 
Genus CLAVATULA, 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 Prerrona, Schumacher, 1817 (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. 
