162 INVERTEBRATA OF MASSACHUSETTS. 



Family BULLEAJ^A, Lam. 



Shell thin, rolled up like a scroll ; animal destitute of tentacula, and having 

 the hranchia in a special cavity, at the posterior part of the back, covered by 

 the mantle. 



Genus BULLA, Lin. 



Shell Uiin, oval or cylindrical, the last whorl enclosing all the 

 others., seldom exhibiting any spire ; aperture narrow, nearly the 

 length of the shell, lip sharp. 



Bulla insculpta. 



Shell oval, bluish-while, fragile, the last lohorl enveloping all 

 the others, and covered with minute, regular, revolving lines, with 

 an imperfect opening in the region of the spire. 



Figure 92. 



State Coll., No. 118. Soc. Cab., No. 838. 



Bulla insculpta, Totten ; Silliman's Journ., xxviii. 350, fig. 4. 

 Bulla solitaria ? Say ; Journ. .-lead. jYat. Sc, ii. 245. 



Shell oval, rather broadest before the middle, thin, pellucid, 

 bluish-white ; the last whorl enveloping all the others, wrinkled 

 lengthwise, and covered with minute, close, revolving lines ; the 

 region of the spire is depressed, and sometimes we find there a 

 very small opening ; aperture narrow behind, broad before ; outer 

 lip very sharp, rising in a regular curve backwards above the 

 summit of the shell ; as it ascends from below upon the body of 

 the shell, it becomes a little thickened, and forms a very slight fold 

 at the umbilical region ; a very thin layer of enamel is found 

 covering the inner margin ; umbilicus none. Length ~ inch, 

 breadth ^ inch. 



Found at Martha's Vineyard, at New Bedford, and in the 

 muddy inlets in Roxbury. 



The differences between B. solitaria and B. insciilpla, if there be 

 any, must be very sU^ht. Nor do I see that the two descriptions are 

 at all inconsistent with each other. Still, it is true that the shells from 

 Martha's Vineyard are precisely like some fi'om Charleston, South 



