SHALLOW-WATER STARFISHES 147 



ossicles are reticulated rather than in longitudinal rows, and the 

 transverse ossicles are larger than the radial ; the median row is only 

 a little larger than the others. The papular areas are wider than the 

 plates. Reproduction unknown. 



STEP'HANASTERIAS ALBULA (Stimpson) Verrill. 

 Asteracanthion albulus STIMPSON, Invert. Grand Manan, p. 14, pi. i, fig. 5, 



Stichaster albulus VERRILL, Proc. Boston Soc. Nat. Hist., vol. x, p. 351, 1866; 

 op. cit, 1895, p. 206. Perrier, Arch. Zool. Exper., vol. rv, p. 347, 1875. 



Duncan and Sladen, op. cit., p. 29, pi. 2, figs. 13-17, 1881. Danielssen and 



Koren, op. cit., p. 31, pi. 8, figs. 13-15, 1884. Sladen, Voy. Challenger, 



vol. xxx, p. 432, 1889. 

 Asteracanthion problema STEENSTRUP, Vidensk. Medd. nat. Foren., p. 240, 



1854. Lutken, Gronl. Echinod., p. 30, 1857. 

 Stephanasterias albula VERRILL, Bulletin Essex Inst., vol. i. p. 5, 1871; Expl. 



Casco Bay, p. 353, 1874 ; Check List, 1879 ', Expl. by the Albatross in 1883, 



p. 540, 1885 ; Revision Genera and Species Starfish, Trans. Conn. Acad., 



vol. x, p. 222, 1899. 

 Variety nitida VERRILL, op. cit, 1866, p. 351. 



A small autotomous, finely spinulated species, with five to nine or 

 more usually unequal rays, normally with six when full grown (var. 

 nitida) . 



In the small specimens, while dividing, there are usually two or 

 three longer, and two to four shorter rays. Mature specimens may 

 have the larger radius 50 mm. ; lesser, 6 mm. 



The dorsal plates in the larger specimens bear about eight to 

 twelve small, crowded, divergent, costellate and rough-tipped spin- 

 ules ; the median series may be a little larger and distinct. About five 

 close-set, alternating dorso-lateral rows of clusters of spinules proxi- 

 mally; inferomarginal plates bear three to five distinctly larger and 

 longer spines. 



Adambulacral plates bear two or three (sometimes four in large 

 specimens), very slender, obtuse spines. 



Major pedicellariae small, lanceolate or ovate ; they occur in a row 

 on the inner edge of the ambulacral furrow ; on the interradial areas ; 

 and sometimes on the adambulacral spines; a few dorsal ones are 

 much larger, stout-ovate, twice as thick as the spinules. Minor pedi- 

 cellariae small, with abruptly spatulate valves, nearly as thick as the 

 spinules, numerous between the spines, above and below. Papulae 

 rather large, mostly in pairs or single. 



This is a circumpolar species. Its range extends to Greenland, 

 Iceland and other parts of the Arctic Ocean, and the northern coasts 

 of Europe and Asia. 



