ARCTIC SEA TO THE WEST OF GREENLAND. 27 



Description of 'the Illustrations of this Species on Plate II. 



Fig. 4. Abactiual aspect of the animal : reduced one half. 



5. Actinal aspect of the same specimen : reduced one half. 



6. Portion near the middle of a ray, actinal aspect: magnified. 



7. Portion near the middle of a ray, abactinal aspect : magnified. 



8. A similar portion from the more compactly spinulated variety of this 



species : magnified. 



GKffiNLANDicuM (Steenstrup), iMken. Plate II, Figs. 9-12. 



1852. ? Uraster violacea, Forbes (non Miiller), Sutherland's ' Journal of a Voyage,' vol. ii. Append, p. ccxiv. 



1853. Asterias Miilleri, Stimpson, Syn. Mar. Invert. Grand Manan, p. 14. 



1854. Asteracanthion Miilleri, Bars ?, var., Steenstrup, Vid. Meddel. N. Forening i Kjobenhavn, 1854, p. 240. 

 1857. Asteracanthion grcenlandicus, Liitken, Vid. Meddel. N. Forening i Kjobenhavn, 1857, p. 29. 

 1863. Asterias grcenlandica, Stimpson, Proc. Acad. N. Sci. Philad. 1863, p. 142. 



1866. Asterias grcenlandica, Verrill, Proc. Boston Soc. Nat. Hist. vol. x. p. 357. 

 1866. Asterias grcenlandicus, Gray, Synop. Spec. Starfish Brit. Mue. p. 2. 



This species maintains a small habit, with five moderately thick arms, the propor- 

 tion of disk-radius to arm-radius being 1 : 4>5 or 5. The ambulacral spines are rather 

 long and cylindrical, and stand, in very irregular alternation, two and one to each adam- 

 bulacral plate, the single spinelets having a position vertical to the floor of the furrow, 

 whilst the pairs, on the other hand, radiate apart from one another in opposite direc^ 

 tions. Except in young individuals, or near the extremity of the ray, the pairs are more 

 numerous than the isolated spinelets, and are generally borne by two or three plates in 

 succession, some rays even being regular for nearly half their length. The lateral spines, 

 which occupy the sides of the ray, form, according to age, either two or three longitu- 

 dinal series of isolated spinelets, not quite so long as the ambulacral series, and tapering 

 slightly at their tips the middle series, when present, being smaller than the others, 

 and placed midway upon the lateral imbricating pieces. At the base of each of these 

 lateral spines are a number of pedicellaria? forcipiformes, sometimes grouped and some- 

 times forming a more or less perfect encircling wreath, the latter generally upon the 

 lower series. 



The ossicles of the abactinal network that lie in the longitudinal direction of the 

 ray are much shorter than those that occupy a transverse position ; and being of delicate 

 habit, the membranous interspaces are consequently large, as well as much broader than 

 long. The dorsal spinelets are finer and shorter than those of the ventro-lateral series, 

 and are placed in groups of two or three together at the intersections, whilst isolated 

 spinelets occupy the intermediate intercalary ossicles, by which means, in consequence 

 of the above-noted proportions of the elements of the calcareous framework, the cha- 

 racter (although somewhat an irregular one) of a transverse arrangement of spinelets 

 across the ray is produced. Upon the disk the spinelets are more closely placed ; and 

 this, in specimens preserved in spirit, gives quite a distinct appearance to that portion of 



