306 INVERTEBRATA OF MASSACHUSETTS. 



tenth of an inch apart, with minute, intervening striae ; with 

 twelve or thirteen longitudinal, obliquely waved, elevated ribs or 

 plaits, traversing the upper whorls, fading away on the con- 

 vexity of the lower whorl, and generally disappearing entirely a 

 short distance from the lip ; a yellowish-brown, velvety epidermis 

 covers the shell wholly, or near the lip ; whorls six, regularly con- 

 vex ; aperture oval, about one half the length of the shell, white 

 within, or more frequently of a brilliant golden-yellow ; minute 

 striffi, corresponding to the prominent lines without, extend some 

 distance within the mouth, and produce faint crenulations of the 

 outer lip ; this is somewhat everted, and arched so as often to 

 produce a conspicuous notch at about its posterior third ; colu- 

 mella broadly overlaid with callus, somewhat flattened, and 

 twisted at its lower portion ; not extending so far as the lip on the 

 opposite side of the canal. Usual length 3 inches, breadth ly\ 

 inch. 



It is occasionally found on some of the rocky bars in Bos- 

 ton harbour, particularly Faun Bar, of good size and beauty. 

 On the sandy beaches it is thrown up, in a worn state. Still far- 

 ther eastward it becomes abundant ; and the finest I have ever 

 seen were sent to me by Dr. Mighels, from the vicinity of Port- 

 land. I am not aware that it is found south of Cape Cod. 



I have given a description of our B. imduiimi, as it most commonly 

 appears with us. It diflers, however, in several points from the Eng- 

 lish shells, as figured and described by Pennant, and others. It is more 

 ventricose, the whorls are one or two less in number ; it is not found 

 of so large a size, British specimens being mentioned four or five in- 

 ches long, while the largest I have seen is only three inches and a half; 

 the striation is far more conspicuous, and the remarkable projection of 

 the columella beyond the rest of the shell, shown in foreign specimens, is 

 not found in ours ; the aperture is proportionally broader, and the ribs 

 or folds less distinct. Its golden mouth, too, which is not found in for- 

 eign shells, renders it a beautiful shell. In truth, it much more nearly re- 

 sembles Pennant's B. striatum, {Brit. Zool., pi. 74) ; but Turton states, 

 that, in the B. striatum (which is now regarded as a variety of B. 

 undatimi,) the shell is much thinner than the true B. uiiddtum, which 

 is not the case in our shell. 



Kiener observes, that this species is very variable in size ; also in its 



