ASTKKOIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER. 179 



Anatomical notes. — Superambulacral plates present though small. Thev are 

 fitted into the angle between lower end of ambulacral and actinal intermediate 

 plates and are A-ery inconspicuous unless treated with caustic potash. They are 

 absent from the tirst ambulacral and at the end of the ray for a considerable number 

 of plates. The longest supcrambulacrals are less than one-third height of exposed 

 surface of corresponding ambulacral. Gonads in a thick much-branched tuft on 

 either side of interrailial septum. Anus present, small and inconsf)icuous. Intesti- 

 nal coecum large, divided into two digitate halves, one with four the other with 

 six palmately arranged lobes. Strong retractors of stomach present. Inter- 

 radial septa single, thick and apparently muscular, but containing no calcareous 

 deposits. Tube-feet large in two rows, %vith broad sucking disk; no deposits. 



Type.— C&t. No. 22332, U.S.X.M. 



Type-localiti/. — Albatross station 425.3, Stephens Passage, Alaska, in 131 to 

 188 fathoms; rock and broken shells. (1003 coll.) 



Distribution. — From the end of the Aleutian Chain to Washington, 34 to 188 

 fathoms; on rocks. 



Specimens examined. — Tloree; besides the type, one from station 2879, off 

 Washington, 34 fathoms, rocks; (U. S. Nat. Mus. coll.); one from 4784, near Attu 

 Island, Aleutian Chain, 135 fathoms. (Albatross, 1906 coll.) 



Subfamily T'SBJTJDARCHA.S'rERIN^^l Sladen 1889 (extended). 



Pseudanhasterinx Sladex, Challenger Asteroidea, 1889, p. 109. — Verbill, Trans. Conn. Acad., 



vol. 10, 1899, p. 187 (extended). 

 Astrogoniinx Perkier (part), Exp^. sci. du Travailleur et du Talisman, 1894, pp. 337, 338. 

 Pseudarchasleridx Fisher, Bull. Btir. Fisheries for 1904, vol. 24, 1905, p. 303; idem, 1903, pt. 3, 



1906, p. 1036. 



Genus PSEUDARCHASTER Sladen. 



Pseudarchaster Sladem, Narr. Challenger Exp., vol. 1, 1885, p. 617; Challenger ksiexo\Ae&, 1889, 

 p. 109. Type, Ps. discus «.— Verrill, Trans. Conn. Acad., vol. 10, 1899, p. 189. 



Astrogonium (part) Perkier (not of Miiller and Troschel), Exp^d. sci. du Travailleur et du 

 Talisman, 1894, p. 338. 



Diagnosis. — Abactinal plates paxilhform, usually more or less stellate, arranged 

 in radial rows, the median largest; papulae usually si.x about a plate, commonly absent 

 from distal half of ray. Marginal plates thick, nioderatelv large, paired, with fas- 

 ciolated grooves between them. Supcromarginals usuall}- separated throughout 

 length of ray, one to three series of paxillffi attaining terminal plate. They are 

 covered with close granules or small, crowded appressed spinelets, the infert>- 

 marginals sometimes with enlarged appressed spinules in a transverse series or group. 

 Adambulacral jilates usually broad vnth convex or angular furrow margin, and few 

 furrow spinelets in palmate series. Actinal intermediate jjlates numerous, arranged 

 in rows running from adambulacral to infcromarginals often also forming parallel 

 longitudmal series; these plates either simply granulous, or with slender spinelets, 

 often with an enlarged spinule on maaay plates. Mouth plates large and prominent, 



o No species is mentioned in the original description. Strictly, the genus had no status till 1889; 

 Ps. discus is the first species. 



