454 Prof. P. M. Duncan and Mr. W. P. Slaclen on 



lacral spines rather long and cylindrical, arranged (in very 

 irregular alternation) two and one to each plate. The double 

 spines radiate in opposite directions, the single ones standing 

 vertical to the floor of the furrow. Except in young indivi- 

 duals, and near the tip of the arm, the double series are the 

 most numerous, being generally borne by two or three plates 

 in succession. After these follow two or three (according to 

 age) longitudinal series of separate spines, not quite so long 

 as the ambulacral spines, and tapering slightly at their tips. 

 The middle series, when present, are smaller than the others, 

 and placed midway upon the lateral imbricating pieces. At 

 the base of each of the spines of these three series is a circlet 

 of pedicellaria3. The ossicles and interspaces of the calcareous 

 network on the abactinal surface of the rays present a very 

 transversely elongate arrangement, in consequence of which 

 the spinelets springing from the imbricating pieces assume 

 the character (though irregularly) of a transverse position 

 across the arm. The dorsal spinelets, which are much finer 

 and shorter than the ventro-lateral series, are arranged in 

 groups upon the ossicles, and in specimens preserved in spirit 

 are more than half-covered by the thick corrugated skin which 

 invests the body. The pedicellariee are, as a rule, not very 

 numerous upon the dorsal surface. The papulge are single. 

 Upon the disk the spinelets are more closely placed ; and this, 

 in spirit-examples, gives quite a distinct appearance to that 

 portion of the animal, whilst in some specimens the disk- 

 spinelets are rather longer than those which are found upon 

 the rays. 



Dr. Llitken is of opinion that this is the species cited by 

 Forbes under the name of Uraster violaceus^ from Assistance 

 Bay (Capt. Penny's Expedition) *. It seems probable to us, 

 also, that the Asterias violacea^ in Sabine's Report on Parry's 

 second voyage, is likewise A. grdnlandicus^ since the Asterias 

 ruhens, Fab. (non Linne), also there mentioned, is referable 

 to A. polar is y M. & T. 



AsteracantMon polariSy Mllller and Troschel. 



Asterias ruhens, Fabricius (non Linne), Fauna Gronl. p. 369. 



A. minuta, Fabricius, =A. polarisjuv. (teste Llitken). 



? A. rnhetts, Sabine in Suppl. Parry's Voyage, &c. 



?A. ochotense, Brandt, Rec. Act. Acad. St. Petersb. 1834, p. 269. 



Asteracanthion polaris, Miiller & Troschel, Syst. d. Asteriden, p. 16. 



Some large specimens were taken on the Torske Bank, 

 Greenland, on the outward journey ; and several young exam- 



* Vidensk. Meddel. 1857, Overs. Gronl. Ecliin. p. 29. 



