ARCTIC SEA TO THE WEST OF GREENLAND. 29 



noted may mark the effect of conditions of environment, and thus represent the steps of 

 an actual locational divergence in the species under notice. A much larger series is 

 needed, however, from various localities, before a definite statement can be made upon 

 this subject. 



Distribution. 



a. Northward of Smith Sound : Discovery Bay, lat. 81 41' N., 25 fms. (Nares's 

 Exped.), the most northern locality on record ; Port Foulke (Stimpson). 



b. North of American Continent : Assistance Bay (under the name of Uraster 

 violaceus, Forbes, Penny's Exped.); Labrador (Packard); Newfoundland (Lutkeri); 

 Gulf of St. Lawrence, near Anticosti ( Verrill) ; Grand Manan (under name of A. 

 Mullen, Stimpson). 



c. North of European Continent: Off S.W. coast of Novaya Zemlya, lat. 71 6' N., 

 long. 50 E., 62 fms. ('Willem Parents' Exped.). 



Description of the Illustrations of this Species on Plate II. 



Fig. 9. Abactinal aspect of the animal : natural size. 



10. Actinal aspect of the same specimen : natural size. 



11. Portion near the middle of a ray, actinal aspect; magnified. 



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



STICHASTER ALBULUS (Stimps.), Verrill. Plate II, Figs. 13-17. 



1842. Asteracanthion roseus (pars), Miiller and Troschel, System der Asteriden, p. 17. 

 1853. Asteracanthion albulus, Stimpson, Syn. Mar. Invert. Grand Manan, p. 14. 

 1855. Asteracanthion prollema, Steenstrup, Vid. Meddel. N. Forening i Kjobenhavn, 1854, p. 240. 

 1857. Asteracanthion problema, Liitken, Vid. Meddel. N. Forening i Kjobenhavn, 1857, p. 30. 

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

 1866. Stichaster albulus, Verrill, Proceed. Boston Soc. Nat. Hist. vol. x. p. 351. 



1875. Stichaster albulus, Perrier, Stellcrides du Museum, p. 82 ; Arch, de Zool. exp. et gen. vol. iv. 

 p. 346. 



A small Starfish with narrow disk and rounded or somewhat arched rays, the num- 

 ber of which is almost invariably six, three rays on one side being as a rule very much 

 shorter than those on the other. Proportion of the diameter of the disk to that of 

 the arms 1 : 5 or rather more. The ambulacral furrows are wide, with suckers arranged 

 in zigzag series, forming two or four rows, according to age and size. Each adambu- 

 lacral plate bears two "ambulacral" spines which radiate slightly right and left, and 

 form regular rows ; occasionally in larger specimens an additional spine accompanying 

 the ten or twenty innermost pairs of the ray. Closely succeeding to these, there fol- 

 lows on the side of the arm a slightly oblique series of three (or, in large specimens, 

 four) similar spinelets, representing ventro-lateral spines, but not always a series opposite 



