236 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



series of actinal intermediate plates ; papulae distributed all over disk 

 and as far along radii as the adradial plates extend. 



This curious genus bears about the same relation to Paragonaster 

 that PHonaster bears to Goniopecten, or Pectinidiscus to Gtenodhciis. 

 In all the characters except those mentioned in the diagnosis it is 

 essentially similar to Paragonaster. 



PERISSOGONASTER INSiCNIS Fisher. 



Plate 73, fig. 1 ; plate 74, fig. 2 ; plate 91, figs. 8, 8a. 

 Perissoffonaster inaignis Fisher, 1913o, p. 628. 



Diagnosis. — Similar in general appearance to a Paragonaster. 

 ■with unusually large disk, stout rays, and the adradial plates ex- 

 tending in large specimens a third to two-fifths length of ray. 

 R=:113 mm., r=35 mm., R=3.2 r; breadth of ray at midinter- 

 brachium, 40 mm., thence tapering gradually to the bluntly pointed 

 extremity; interbrachia wide and arcuate; superomarginals 37 to 42, 

 broader than long, and increasing slightly in width up to the tenth 

 or twelfth, and beyond the eighth to seventeenth separated only by 

 the rectangular carinal plates; odd interradial plate similar to the 

 rest ; plates covered with depressed, roundish, convex, slightly spaced 

 granules, the outer end being armed with an inconspicuous, short, ap- 

 pressed, slender, sharp spine extending nearly to end of ray ; inf ero- 

 marginals narrower on outer two-thirds of ray than superomargin- 

 als and covered with conical granules; in addition to these, proxi- 

 mally 6 to 10 and distally 2 to 4 slender, sharp, appressed spines, 

 either scattered or in 1 or 2 transverse series; abactinal plates pax- 

 illiform, with compact subhexagonal crowns, very regularly ar- 

 ranged in series parallel to the radial; an average radial plate with 

 9 to 12 roundish or slightly polygonal, spaced, central granules and 

 20 to 25 flattened, truncate, oblong, or slightly tapered, smaller 

 peripheral ones, these numbers increasing on the distal carinal plates 

 and decreasing on the dorsolaterals; papulae distributed all over 

 dorsal surface as far distad as there are more than 1 series of 

 abactinal plates ; actinal intermediate plates, each with an appressed, 

 sharp spine; adambulacral plates with an angular but not very 

 salient furrow margin bearing 6 or 7 short, blunt spines; subambu- 

 lacral spines 1 or 2, sharp, appressed, surrounded by 5 to 8 elongate, 

 subconical granules, in addition to 3 or 4 on outer margin, and 3 to (> 

 on each transverse margin, the latter often forming a fasciolate 

 pedicellaria over the suture. 



Description. — The rays taper somewhat arcuately from the mid- 

 intorbrachium and in form are more like those of Pseudarchaster 

 than the usual verv attenuate condition of Paragonaster. Area of 



