1885.] REVIEW OP THE NORTHERN BUCCINUMS. 383 



usually bluish with chestnut-brown revolving lines, or series of 

 spots, or patches ; sometimes brown with white spots. Periostraca 

 smooth or short-ciliated. 



Operculum elliptical ; nucleusL.distant from the outer margin 

 about a fifth of the total width. Central tooth of the lingual 

 ribbon with five equal denticles ; lateral tooth with three. 



The dimensions of an adult specimen from Northern Greenland 

 are, length, 2.3 ; breadth, 1.3 inch. The species is however very 

 variable in size, dwarf specimens with the full number of whorls 

 frequently occurring. There is a slender dwarf form (Humphrty- 

 slanum Moell., non Bennett) occurring in the Greenland seas, 

 which, with six whorls, is only one inch in length. The specimens 

 of the ordinary form, of that length, would have but four whorls. 

 Yet all the dwarfs have the characteristic striation, and must, with 

 little doubt, be referred to the same species. 



B. cyaneum may be distinguished from the young of B. unda 

 turn and B. undulatum by the delicacy of the primary transverse 

 ridges and especially by the absence or obsolescence of the folds on 

 the columella ; from B. plectrum by the shortness of the longitu- 

 dinal folds, and the coarser secondary ridges ; from B. Humphrey, 

 sianum, by the more slender shell, less convex whorls, and less numer- 

 ous and less crowded primary ridges ; and from B. groenlandicum by 

 want of the regular, parallel and sharp cut primary grooves which 

 characterise that species in common with others of the glaciate 

 group. I have mentioned the B. groenlandicum, though not an allied 

 species, because the primary ridges of the cyaneum in some spe- 

 cimens might be mistaken at the first glance for the carina of that 

 species, both shells being of a thin and delicate structure. 



The cyaneum is a North Atlantic species, ranging as far into 

 the arctic regions as exploration has yet extended. Southwardly 

 its geographical limits reach but little beyond the Arctic circle on 

 the shores of either continent. It is abundant in all parts of the 

 seas of Greenland, even to Port Foulke on the north-western 

 coast, from which place I have specimens brought home by Dr. I. 

 I. Hayes of the American Arctic expedition. Hancock reports 

 it from Davis Straits, its southern limit, as an existing species, on 

 our coast. It is common on the northern coast of Norway and 

 Lapland. As a fossil it occurs in the Pleistocene of Riviere-du- 

 Loup, Canada, in fine condition, and as large as the specimen from 

 northern Greenland, the dimensions of which are given above. 



