8§ PTERASTERIDAE. 



giganteus Sladen, 1891. Proc. Roy. Irish Acad., ser. 3, 1, p. 696. Southwest of Ireland, 750 fms. 

 giboryi Perkier, 1894. Travailleur et TaUsman Stell., p. 189. Between Azores and Europe, 2,218 fms. 

 rex Perrier, 1894. Ibid., p. 186.1 Eastern North Atlantic, 623-1,248 fms. 



regalis Verrill, 1895. Amer. Journ. Sci. ser. 3, 49, p. 203. Off southern New England, 1,374 fms. 

 regalis var. agassizii Verrill, 1899. Trans. Conn. Acad., 10, p. 221. Off southern New England, 



1,242 fms. 

 perspicuus Lttdwig, 1903. Belgica Seesterne, p. 30. Antarctic Ocean, southwest of Alexander the 



Fu-st Land, 222-250 fms. 

 gvadrispinosxis Fisher, 1905. Bull. U. S. Bur. Fish., 24, p. 315. Off San Diego, Cal., 1,059 fms. 

 platyacanlhus LuDwao, 1905. Mem. M. C. Z., 32, p. 191. Panamic region, 1,359-1,572 fms. 

 ■purpureus LtTDWiG, 1905. Ihid., p. 194. Between Cocos Island, and Panama, 1,470 fms. 

 violacexis Ltjdwig, 1905. Ihid., p. 196. Southeast from Acapulco, Mexico, 1,877 fms. 

 gracilis Ludwig, 1905. Ibid., p. 198. Panamic region, 1,321-1,771 fms. 



penlagonalis Fisher, 1906. Hawaiian Starfishes, p. 1099. Hawaiian Islands, 289-334 fms. 

 roseus Koehler, 1907. Bull. Inst. Ocean., no. 99, p. 21. Eastern North Atlantic, 1,009-1,148 fms. 

 campanulatus Koehleb, 1908. Trans. Roy. Soc. Edinburgh, 46, p. 550. WeddeU Sea, 1,410 fms. 

 densus Koehler, 1908. Ibid., p. 554. Weddell Sea, 2,620 fms. 

 edax Koehler, 1908. Ibid., p. 552. East of South Orkney Islands, 1,775 fms. 

 fucatus Koehler, 1908. Ibid., p. 553.^ Weddell Sea, 1,410 fms. 



alcocki Koehler, 1909. Investigator Deep Sea Ast., p. 110. East side. Bay of Bengal, 643 fms. 

 koehleri Fisher, 1910. Ann. Mag. Nat. Hist., ser. 8, 5, p. 170. Bering Sea, 1,771 fms. 

 perissonotus Fisher, 1910. Ibid., p. 170. Off San Diego, California, 984 fms. 

 bartschi Fisher, 1916. Proc. Biol. Soc. Washington, 29, p. 29. Sulu Sea, 1,105 fms. 

 rhodopeplris Fisher, 1916. Ibid., p. 29. Gulf of Tomini, Celebes, 834 fms. 



The form which Verrill described as a variety (agassizii) of regalis seems 

 undoubtedly a valid species as it differs from regalis in several fundamental 

 points. 



The characters which seem of the most importance in distinguishing the 

 species of Hymenaster are the armature of the oral plates and of the adambula- 

 cral plates. In most species the number of adambulacral spines, of oral spines, 

 and of suboral spines is remarkably constant. In a few cases, we find three 

 adambulacral spines where the typical number is two, or four where three is 

 usual, and if the number of oral spines is three, there may occasionally be four, 

 while if the number is usually four or five it may run up to seven. The number 

 and form of the suborals is less hable to diversity, but owing to sUght shifts of 

 position or some diversity in size, it is often difficult to decide whether the spine 

 nearest the inner end of the oral plate is a suboral or the innermost oral. Careful 

 consideration of its relation to the other orals wiU generally determine the 

 point however. Thus in carnosus, Sladen says there are two suborals but 

 admits that the inner is perhaps an oral; his figure shows that it is best consid- 

 ered the innermost oral. In quadrispinosus Fisher, it is possible, as that author 



' These two species of Perrier were named and the names were published in 1885 but with no descrip- 

 tion or figures; the names therefore must date from 1894. 



^ These four species of Koehler were mentioned and named in 1907, Zool. Anz., 32, p. 144, but as 

 the diagnoses are wanting or wholly inadequate, the names must date from the fuU report. The Hymen- 

 aster scotiae of the 1909 Zoological Record is a slip of the pen for Ilyphalaster scotiae. 



