4 GENUS PYRAMIDELLA. 
is always narrowest ; the others are wider and deeper colored. 
Spire pointed, composed of from ten to twelve distinct whirls, 
smooth, slightly convex. Aperture ovate, sub-rotund at its 
base, and generally marked within, with very prominent ridges 
continued upon some specimens even to the edge of the right 
lip, which is sharp; columella slightly arcuated, recurved 
around the umbilicus ; it is furnished at its base with three 
folds, the upper of which is more prominent than the others. 
Umbilicus small, cylindrical, narrow and deep. 
Length 16 lines. Width 7 lines. 
Inhabits the American seas among the Antilles. 
We find in this species some variations of color. Some shells 
are violet with all the bands brown, others are of a dull white, 
with narrower and less numerous lines. With Deshayes we 
think the PyramipeLua dolabratum a very old terebellum of La- 
marck ; for it differs from that only by the ridges which are 
found at the internal part of its left lip, so that if the edge of the 
lip happens to be broken, this edge has the appearance of being 
denticulated; it is this accident alone, frequently occurring, 
which has caused the separation of these two species; for in the 
specimens remaining perfect, the folds are seen only within the 
aperture. Very old specimens have ialso the folds of the colu- 
mella strongly marked. In other respects there is a perfect 
similarity in the characters of the two species. 
2, PYRAMIDELLA VENTRICOSA, Quoy et Gaim. The 
Swollen Pyramidella 
(Collect. Mass. Lam.) 
Pl. I, fig. 1. 
P. test4 ovato-turrita, ventricosd, apice acuti; anfractibus convexius- 
culis, lineis longitudinalibus rufescentibus vel fuscescentibus undulatim 
ornatis, ultimo ventricosiusculo ; apertura ovata, albida. 
Shell ovate, turreted, polished, pomted at its summit, 
indistinctly striated in its whole length ; spire composed of ten 
slightly convex whirls, the last a little swollen and whitish, all 
