82 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 109 



axial cords continue across the base to at least the second spiral cord 

 (pi. 3, fig. 4). 



Form 2. Typified by a shell of perhaps 3 whorls (nucleus eroded) 

 from 741 feet (pi. 3, fig. 2). The periostracum of this shell is dark 

 brown, appearing almost black when wet. The somewhat wavy and 

 sometimes interrupted axial cords of the last whorl are intermediate 

 between those of Form 1 and Form 3 and are twice as numerous 

 as those in Form 3, hence are narrower and have narrower interspaces 

 between. These cords are interrupted at the base by a beaded cord 

 that sm"rounds the umbilicus and terminates about the middle of the 

 summit of the peritreme. Two more beaded cords, and a short and 

 inconspicuous third cord, disappear into the umbilicus. The post- 

 nuclear whorl has coarser axial cords separated by somewhat wider 

 interspaces than those of the last whorl. A younger specimen, also 

 dark, from 741 feet, has about 2+ whorls and has only the coarse 

 and more widely spaced axial sculpture on the postnuclear 1 .5 whorls. 

 This sculpture is interrupted at the base by the sphal cord and two 

 more spiral cords disappear into the umbilicus. A third specimen, 

 from 453 feet, is tan colored, has 2.5 whorls, and axial sculptming and 

 spiral cords like the smaller specimen above. The nucleus, of one 

 whorl, is intact. 



Form 3. One specimen (1.9 mm. in diameter) of 3+ whorls 

 (nucleus eroded), light tan in color, from 453 feet (pi. 3, fig. 5). The 

 axial cords are similar on all the postnuclear whorls; they are coarse, 

 perhaps a trifle coarser than those of the postnuclear whorl of Form 2, 

 and are separated by wider interspaces. The umbilicus is not out- 

 lined by a spiral cord, but three short, inconspicuous beaded cords 

 disappear into it. The axial cords are not interrupted at the base, 

 which is convex. 



The specimens examined from other localities exhibit all of these 

 variations and more. A specimen from Holsteinborg, Greenland, 

 has prominent axial cords, another from Gothaab has coarse and fine 

 ribs on the same shell. Three shells from Newfoundland have fine 

 to very fine axial sculpturing — ^too fine to designate as "ribs." Several 

 specimens from Davis Strait also have fine axial sculptiu"ing. In some 

 shells from Spitzbergen there are no visible cords or threads around 

 the umbilicus, in others there are faint threads and in others there are 

 as many as fom- to seven. In some shells there is neither an angle 

 at the base nor beading of the spiral cord or thread, in others there is 

 no angle, the base is rounded, but the spiral cord is beaded. 



The variations described above cannot be accounted for on the 

 basis of depth nor on the type of bottom, for all three of the formes 

 mentioned above from Point Barrow were found at 453 feet. 



