GENUS P YR AM IDELLA. 



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 PYRAMIDELLA dolabratum a very old terebettum 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 also 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, Quov et GAIM. The 

 Swollen Pyramided 



(Collect. MASS. LAM.) 

 PI. I, fig. l. 



P. testa ovato-turrita, ventricosa, apice acuta ; anfractibus convexius- 

 culis, lineis longitudinalibus rufescentibus vel fuscescentibus undulatlm 

 ornatis, ultimo ventricosiusculo j apertura ovata, albida. 



Shell ovate, turreted, polished, pointed at its summit, 

 indistinctly striated in its whole length ; spire composed of ten 

 slightly convex whirls, the last a little swollen and whitish ; all 



