380 THE CANADIAN NATURALIST. [Oct. 



of the outer lip is rather narrow, deep, and near the suture; 

 while in undatum it is broader, shallower, and further forward, 

 nearer the middle of the lip. In undatum the surface within the 

 aperture is always white or chocolate-colored, while in the American 

 species, as Dr. Gould* has already pointed out, it is often saffron 

 colored. The columella is shorter (less projecting below) in the 

 American shell than in the European. Finally the ciliation of the 

 periostraca in undulatum is short and sparse, never long and furry 

 as is commonly the case in good specimens of undatum. 



Our shell never reaches the size nor the number of whorls of 

 the European form. I have one specimen from Labrador four 

 inches in length, but the average size of adults is much less than 

 the average of foreign shells. A good example from Maine 

 measures 3 inches in length, and 1.8 inch in breadth. 



From President Dawson, I have received specimens from the 

 St. Lawrence River, which were taken from water somewhat 

 brackish. The influence of an uncongenial element is plainly 

 perceptible in them. They are much thinner and smoother than 

 normal examples, but would not be confounded with any of the 

 smooth species described elsewhere in this paper, such as B. 

 cyaneum ; for the character of the striation, though but faintly 

 indicated in these specimens, is still the same as that of the 

 typical examples. 



There can be but little doubt that our shell is the same as the 

 undulatum of Moeller, as it agrees in all respects with that author's 

 description. The figure of Reeve is good, but his description is 

 erroneous in the expression " whorls tranversely very finely 

 striated." Our shell ranges further north than the European 

 undatum, being adapted to a colder climate. Its northern limit 

 is Southern Greenland, where, however, it is rare. Its southern 

 limit, as far as ascertained, is on the sea-bottom off the coast of 

 New Jersey, in N. lat. 40°, W. long 73°, where it was dredged by 

 Capt. Gedney, U. S. N., in thirty-two fathoms, sandy bottom. Like 

 many other cold-water species it lives there in the polar under- 

 current which flows beneath the gulf stream, and in a contrary 

 direction. I have also specimens from Labrador, Newfoundland, 

 the Gulf and River of St. Lawrence, Nova Scotia, Grand Manan, 

 the coast of Maine, Massachusetts Bay, Cape Cod, and Nantucket. 



* " Its golden mouth, too, which, is not found in foreign shells, renders 

 it a beautiful shell." Gould, Inv. Mass., p. 306. 



