BULLEANA. MOLLUSCA. BULLA. 165 



the shell, widening from behind forwards ; outer lip attached be- 

 hind, a little before the summit of the shell, it rises to a level with 

 the spire, and then descends in a regular, though slightly waved 

 curve to the front of the pillar, where it terminates quite abruptly ; 

 inner lip spread out in a thin enamel upon the body of the sheU, 

 partially covering an umbilical indentation placed at about one 

 fourth the length of the shell. Length T l - inch, breadth i inch. 

 Obtained from fishes taken in Massachusetts Bay. 



This shell has no marked resemblance to any other with which I 

 am acquainted, unless it be to B. Gouldii, of which it may possibly be 

 the young. It is, however, much smaller and thinner, more globular, 

 and its greatest breadth is before, instead of behind, the middle. The 

 peculiarity of the base, also, is well marked. In many respects, it has 

 a general resemblance to Montagu's B. didphana, ( Test. Brit. pi. 7, f. 

 8,) but that has an elevated spire, and is not umbilicated. Brown 

 figures a shell, which he calls Didphana pellucida, (Conch, of Great 

 Brit., &c., pi. 38, f. 10, 11,) which bears a still more striking resem- 

 blance. 



These two last named species would come under the sub-genus 

 APLU'STRE of Blainville ; in which the whorls are all visible, but the 

 spire not projecting; and in which there is a thickened portion at 

 the anterior termination of the pillar. 



BULLA TRITI'CEA. 



Shell cylindrical, smooth, whitish, of the size of a grain of rice, 

 a pit in place of the spire. 



FIGURE 98. 

 State Coll., No. 116. Soc. Cab., No. 3871. 



Bulk triticea, COUTHOUV ; Bost. Journ. Nat. Hist., ii. 88, pi. 2, f. 8. 



Shell cylindrical, polished, rather solid, of a dull white color, 

 and covered with a thin, rusty epidermis ; marks of growth very 

 delicate, and numerous minute revolving lines may be seen under 

 a magnifier ; a circular pit occupies the region of the spire, from 

 the margin of which the outer lip takes its origin, and, rising a 

 little, passes forward in a direction nearly parallel to the left 

 margin of the shell, forming a long, narrow aperture, which sud- 

 denly becomes double this breadth, near the front, by the curva- 

 ture of the inner lip ; occasionally the lip is a little waved in- 



