82 CLASS GASTEROPODA. 
STROMBUS (proper), Lam., 
In which the margin expands into a wing of more or less ex- 
tent, but not digitated. The foot is proportionally small, and 
the eyes are supported on lateral pedicles of the tentacula, 
thicker than the tentacula themselves ; the operculum is horny, 
long, and narrow, and placed on a thin tail. Nearly all the 
strombi comprised in the second and third division of Gmelin, 
observing, that owing to the various degrees of development 
acquired by the external margin, there are several repetitions. 
PTEROCERA, Lam. 
The margin in the adult is divided into long and slender 
digitations, varying in number, according to the species. The 
animal is the same as that of the true strombus. (Strombus 
lambis, Rondel. 79, &c.) . . 
In other strombi the sinus of the external margin is con- 
tiguous to the canal, forming the ROSTELLARIA, Lam. ‘There 
is usually a second canal ascending the spire, formed by the 
external margin, and by a continuation of the columella. 
In some of them the margin is still digitated. Their animal 
resembles that of a murex, but has only a very small oper- 
culum. (Strombus pes pelicani, L., &c.) 
In others we merely observe a detached margin. Their 
canal is long and straight. (Strombus fusus, L.) 
In some, again, that margin is entire; they are the HIPPo- 
CRENES, Montf. (Strombus amplus, L.) 
