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 

 striae, 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 1 T 9 

 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. undatum, as it most commonly 

 appears with us. It differs, 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. stridtum, (Brit. Zoo?., pi. 74) ; but Turton states, 

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

 unddtum^) the shell is much thinner than the true B. undatum^ which 

 is not the case in our shell. 



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



