ASTEROIDEA OF NOKTH PACIFIC AND ADJACENT WATERS — FISHER. 17 



6-. I'odicellarise pedunculate, either forcipLform or forficiform (crosfled or straight); actinostomo with 

 ambulacral phites prominent except in lirisingida;. Skeletal plates bearing spines, often long 

 and isolated, on or about which are usually grouped the pedicellariap; or the pedicellarije may 

 be isolated; marginal plates inconspicuous or aborted; ambulacral plates often very crowded 

 with tube foot in four series. Abactinal skeleton formed of skeletal arches (transverse on rays ) 

 independent or bound together by intermediate plates, forming a network with rectangular or 

 very irregular meshes. These skeletal arches correspond to every other or to every third adambu- 

 lacral, and are composed of pieces corresponding in the ventral, lateral, and dorsal regions of the 

 body. Mouth plates usually in<onspicuous Forcipuhia Perrier. 



Order PHANEROZONIA Sladen, 1889. 



=PA.xiLLOsA-f-VALVATA (Valvulata) Pcrrier, 1884, 1894,+Notomvota Ludwig. 1910. 

 With the characters given above. 



KEY TO THE KNOWN FAMILIES OF PHANEROZONIA. 



l'. Tube feet pointed without a definite fiat sucking disk, but sometimes with a small pointed knob at tip. 

 6'. -Vmpullse single, one to each tube foot. No intestine, no intestinal ccpcum. no anal pore. Mar- 

 ginal plates thin and lamelliform. Cribriform organs between the marginal plates. 



Porcellanasteridse, p. 22. 

 c'. No actinal fascioles; cribriform organs localized in interradial arcs; no superambulacral plates; 

 paxillae or simple embryonic abactinal plates with a few epicular apinelets. 



Porcellanasterinx, p. 23. 

 C-. Actinal fascioles; cribiform organs of a simple nature and between all the marginals; super- 

 ambulacral plates present; paxilla Clenodiscinx, p. 31. 



6". Ampullae double; simple cribriform organs, or more or less specuilized marginal fascioles usually 

 present; abactinal plates always paxilliform; superambulacral plates always present, 

 c'. Superomarginal plates replaced by paxillae; broad inferomarginals; no anus, no intestinal 



coecum, no intestine; compound papulae Luidiidx, p. 10-5 



cr. Superomarginals never aborted, though sometimes small; not replaced by paxUla similar tu 

 those of dorsum; intestine present; coecum only exceptionally absent (Blakiaster): anal pore 

 usually present, frequently of minute size, and sometimes absent; papuliE simple. 

 d'. Marginal, adambulacral, and actinal plates bordered by a single row of spinelets united by a 

 web-like membrane, forming specialized fascioles identical with cribriform organs; mar- 

 ginals and actinals usually covered with thin membrane; actinals in doublt or single 

 interradial series, between which are the specialized fascioles leading from marginal fas- 

 cioles to adambulacrals; adambulacral armature simple usually in a single marginal series; 



paxilla? with marginal spinelets webbed Goniopectinidy. 



(P. Marginal and actinal plates never bordered by a single row of webbed spinelets, nor are spine- 

 lets of paxillse webbed; superomarginals variable; inferomarginals always massive; 

 marginals never overlaid by a smooth membrane; actinal plates never in double interradial 

 series, with each double series separated by specialized fascioles; actinal plates with paxilli- 

 form groups of spines or spinelets; adambulacral armature always in several series, inter- 

 grading into actinal spinelets Astropectinid.r, p. 37. 



^. Tube feet with well-developed sucking dL-fks. 



5'. Abactinal plates paxilliform or tabulate with groups of coordinated granules or spinelets; or in the 



form of spinopaxillse; or simple and flattened with few spinelets (in the latter case the marginals 



are alternate and very spiny). 



c'. Marginal plates appreciably alternate and with sharp conspicuous spines; a pair of muscle 



bands extending along dorsal wall of each ray, from region of third to eighth ambulacral 



ossicle to tip; papulae usually confined to base of ray and adjacent portion of disk, often to a 



localized papular organ Benthopeclinids-, p. 120. 



c'. Marginal plates opposite (at least at base of ray) and not conspicuously spiny; no dorsal muscle 

 bands; papulae not confined to base of ray and adjacent portion of disk and never localized in 

 a special papular organ. 

 57444°— Bull. 76—11 2 



