166 INVERTEBRATA OF MASSACHUSETTS. 



wards at the middle, narrowing the aperture ; at the region of the 

 umbilicus is a flattened, white space, thickened by enamel, 

 gradually disappearing within the aperture ; the whole inner mar- 

 gin is sometimes slightly coated with enamel. Length A inch, 

 breadth j\ inch. 



Found plentifully in the maws of fishes taken in Massachusetts 

 Bay. 



This shell is analogous to the B. cylindracea of Pennant, (Brit. 

 Zool., pi. 70, f. 85.) But that is a much longer shell, and decidedly 

 umbilicated in the region of the spire. Brown figures a shell under 

 the name of Volvdria alba, (Conch, of Great Brit., &c., pi. 38, f. 43, 

 44,) which bears a striking resemblance to this shell. 



BULLA CANALICULA'TA. 



Shell nearly cylindrical, spire somewhat elevated^ with a groove 

 on the summit of the whorls. 



FIGURE 97. 

 State Coll., No. 113. Soc. Cab., No. 2390. 



Volvaria canaliculata, SAY ; Journ. dead. Nat. Sc., v., 2J1. 

 Bullina canaliculata, SAY ; rfmer. Conch., pi. 39. 



Shell cylindrical, white and shining, with very faint lines of 

 growth ; spire a little elevated, crowned with a minute but promi- 

 nent tip ; whorls about five, the summit of each having a shallow, 

 rounded groove ; outer lip arching forwards ; inner lip over- 

 spread with a thin plate of enamel, and having a single oblique 

 fold near the base. 



I have found only one specimen of this shell from the waters of 

 Massachusetts. This was discovered, among other minute shells, 

 in sand brought from Martha's Vineyard. Prof. Adams found 

 them in considerable numbers in New Bedford harbour. 



I have been induced to place this species under the genus BULLA, in 

 consequence of the remarks of M. Deshayes, in his edition of La- 

 marck's work. He thinks the main character of Ferussac's genus 

 BULLI NA, as modified by Blainville, viz., " an apparent and prominent 

 spire," is not of sufficient importance to constitute a genus ; and, while 

 Mr. Say states that the animal of BULLINA differs from that of BULLA 



