Distribution. Beside the material examined, T. borealis is known only from off Newport, Rhode Island, USA in 660 m (Verrill 1882: 486, pi. 57, fig. 18 as Taranis moerchi).
Description. Shell solid, glassy white, composed of 3 postlarval whorls. The outline of the shell is somewhat spiny, due to the strong sculpture of the penultimate and body whorl. The suture is shallow. The larval shell is brown, and consists of a single whorl, with a diameter of 500 µm, covered with spiral rows of granules giving a reticulate appearance. Very fresh adult shells have a microsculpturc of very minute granules. The spiral macrosculpture of the postlarval whorls consists of one subsutural line, one strong keel at the periphery of the whorl and three more strong lines below it on the body whorl. These lines do not occur on the siphonal canal. The axial sculpture consists of bent lines which form nodulous projections when they cross the spiral sculpture. The siphonal canal is short and slightly curved to the columella, which together with the body whorl form a regular curve where they meet.
Dimensions: height of the shell 2.7 mm, breadth 1.45 mm; height of the aperture 0.9 mm, breadth 0.4 mm.
The animal has no operculum and no radula.
Remarks. T borealis can be distinguished from moerchi by its stronger sculpture, smaller number of spiral lines below the peripheral keel and the colour of the larval shell which is white in T. moerchi. T. malmi has similarly a prickly sculpture but the protoconch is multispiral; T malmi has planktotrophic larvae, whereas borealis has direct or lecithotrophic larval development.
Under the name Pleurotoma parvulum (Jeffreys, 1880: 318 nom.nud.) Locard (1897:200) has described a turrid which cannot be identified from the poor figure which is drawn from two specimens: we have examined the type material and found one shell of Taranis malmi with broken protoconch from which the lower part of the drawing of P. parvulum was prepared and one worn shell of Taranis borealis from which the upper part was drawn. However the name parvulum cannot be used for the Taranis described here because it is preoccupied by Pleurotoma parvula Reeve 1845.