1865.] REVIEW OP THE NORTHERN BUCCINUMS. 379 



I have not had an opportunity of examining a specimen of the 

 Buccinum acuminatum of Broderip, described and figured in the 

 " Zoological Journal," vol. v (1850), p. 44; pi. iii, figs. 1, 2. 

 Forbes and Hanley, in their "British Mollusca," consider it to be 

 an abnormal form of B. undatum. 



Buccinum undulatum Moeller. 



Buccinum undatum Greene, Catalogue of the Shells of Massachusetts 

 (1833). Gould Inv. Mass. (1841), 305. DeKay, New York Fauna, v 

 (1843) 130; pi. vii, 161. Dawson, Can. Nat. [2], ii (1865), 88. 



Buccinum undulatum Moeller, in Kroyer's Tidsskrift, iv (1842), 84. 



Buccinum labradorense Reeve, Conch. Icon., iii (1846), Buc, i, 5, 

 Packard, Can. Nat., viii (18Q3), 416. 



Tritonium undulatum Moerch, in Rink's ' Greenland' Tillaeg (1857), 

 Aftr. 84. 



It is not often that two species of shells can be found, the dif- 

 ferences between which are more difficult to define than those of 

 the common whelks of the European and North American shores 

 of the Atlantic. Existing as they both do in vast numbers and 

 occupying a very extensive range in station, — from between tide- 

 marks to a depth of more than fifty fathoms on all kinds of 

 ground, — it is not surprising that we find considerable variation 

 among the very numerous specimens which come under our notice, 

 and that the varieties of the two forms, which occur under similar 

 conditions should approach each other closely. Yet it is not at all 

 difficult in most cases, for one familiar with these forms to tell at 

 a glance whether an adult specimen came from the eastern or 

 western side of the ocean. There is a fades, difficult to describe, 

 which makes the forms easily recognizable. But specific, tangible 

 differences are hard to find. After careful comparison, I have 

 detected none in the soft parts, nor in the lingual dentition, the 

 central tooth in both having six denticles, and the lateral tooth 

 four. Nor can we find differences in the younger half grown 

 shells. With the adult shells I have met with more success, and 

 will endeavor to describe the distinctive features. 



The whorls are more convex next to the suture in undulatum 

 than in undatum, and the suture is consequently deeper. In 

 undulatum also the body-whorl is proportionally broader, and the 

 spire usually shorter ; the aperture is smaller, more circular, and 

 conspicuously more arched within or excavated into the body- 

 whorl at the upper part of the inner lip. In undulatum the sinus 



