154 PLEUROTOMID A, 
Synopsis of Genera. 
I. Pleurotomine. 
Genus PLEUROTOMA, Lamarck, 1799. 
Shell turriculated, fusiform ; spire long, sharp ; aperture ovate, 
the columellar margin smooth, the outer lip with a narrow pro- 
found sinus separated rather distantly from the suture; canal 
long and narrow, straight, open. 
Animal, foot truncated anteriorly, obtuse posteriorly ; tentacles 
cylindrical, with eyes externally near their base; teeth faleiform, 
angulated (1-0-1). Dentition, Pl. 33, fig. 54. Generally large 
shells variegated with spots. Inhabiting warm seas. Fossil, 
tertiary. . 
Subgenus GEMMULA, Weinkauff, 1875. 
Shell spindle-like, canal rather long and narrow, sometimes 
curved ; sinus straight, more or less narrow and long, terminating 
a nodulous peripheral keel ; embryonal whorls three or four, the 
two upper ones smooth, upright, the others longitudinally 
ribbed. 
Consists of a few species having upright embryonal whorls, 
these being inclined in Pleurotoma. 
Genus GENOTIA, H. and A. Adams, 1853. 
Shell narrowly obconic, cancellated, body-whorl gradually 
tapering toa but slightly developed canal; lip-sinus wide and 
shallow; aperture long and narrow, with subparallel margins. 
Operculum unguiculate. 
Animal resembling Conus. 
The name is derived from Génot, by which Adanson called 
the type species. W. Coast of Africa. 
Pseudotoma, Dolichotoma, Oligotoma and Rouaultia of Bel- 
lardi and Cryptoconus, Koenen, are sections containing Huropean 
tertiary species. Their characters are not important. 
Genus COLUMBARIUM, E. von Martens, 1881. 
Shell fusiform, carinated, spiny; embryonic tip of the spire 
globular ; aperture short, oval ; sinus of the lip scarcely indicated 
by a slight curve; canal narrow, very long. W. Australia, China, 
Panama. The group is placed here by von Martens on account 
