and Shells of Massachusetts Bay. 91 
spots which are largest on the two lower whorls; whorls 
ten in number, very convex, barely touching each other; 
crossed by numerous, delicate, slightly elevated, polished 
ribs, to the number of eleven on the body-whorl, each 
forming at its superior portion a distinct mucronation. 
The rib bounding the lip, and several others upon the 
last three whorls are much more robust than the rest. 
‘The interstices of the coste are covered with numerous, 
fine, raised strie, whose intervals are filled with others 
still finer, and which are traversed by exceedingly 
close and minute longitudinal lines, giving the shell, 
under a microscope, a very beautiful reticulated aspect. 
Aperture ovate, lip continuous, formed by a robust rib 
having a spinous projection or aculeation upon its 
outer superior portion, flattened and produced into an 
angle at its inferior columellar extremity, so as partially 
to conceal the umbilicus. 
Ozsservations. This elegant shell, the most beau- 
tiful, perhaps, of all that are found on our coast, has a 
general resemblance to S. multistriata of Say, but differs 
from that shell, in the number and irregularity of the 
coste, as well as in having their summits mucronate or 
crowned, and also in being perforate, which is not the 
case with Say’s shell. S. linedta of Say, has also some 
resemblance to this, but wants the interstitial strie, and 
has, moreover, a slightly elevated line surrounding the 
base, which is not found in our species. S. clathrus, 
Mont., is also distinct, in having the intervals of the 
coste perfectly smooth, in its ribs traversing the sutures, 
and in its being imperforate. I have met with but one 
specimen, taken from the stomach of a cod, off Cape 
Ann, in August last; but this is fortunately pt and 
in a high state of preservation. 
VOL. II.—-NO. I. 
