454 THE VOYAGE OF II.M.S. CHALLENGER. 



Young P/tase. — I Lave referred a small example of Solaster, which measures E = 20 

 mm., from the same locality to this species. It is figured on PL LXX. Although at 

 first sight this juvenile appears to differ considerably from tLe adult, I feel little doubt 

 tbat tLe differences are only due to age. TLe number of rays is tLe same. TLe paxiUse 

 are relatively larger and more distinctly spaced tLan in tLe adult. In the armature of 

 the adambulacral plates tbere are only tLree spinelets in tLe furrow series on tLe plates 

 near tLe moutL, and only two along tLe ray ; tLe transverse lineal series on tLe actinal 

 surface of tLe plates consists of tLree robust spinelets. TLe infero-marginal paxillae form 

 a conspicuous border on tLe actinal surface, similar to wLat Las been observed in tLe 

 adult, and tLe actinal interradial areas Lave a similar spinose cLaracter. TLe armature of 

 tLe moutL-plates consists of a marginal series of eigLt spinelets, tLe innermost one being 

 remarkable for its size and tLe capacious membranous sac witb wLicL it is invested. On 

 tLe actinal surface of eacL plate is one large robust spinelet, aud furtber back on tLe plate 

 two or tLree smaller ones. 



Remarks. — TLis species is very closely related to Solaster endeca, but may be dis- 

 tinguisLed by tLe form and cLaracter of tLe paxillse, by tLe large actinal interradial 

 areas, by tLe broad band of infero-marginal paxillse, and by tLe cLaracter of tLe armature 

 of the adambulacral plates. 



3. Solaster rcgularis, n. sp. (PL LXX. fig. 1 ; PL LXXII. figs. 5 and 6). 



Rays eight. E = 90 to 100 mm. ; r = 20 mm. E = 4 -5 to 5 r. Breadth of a ray 

 at the base 14 mm. 



The disk is high and convex. TLe rays are long, tapering, and attenuate towards tLe 

 extremity ; in the present condition of tLe specimen all are curled over on tLe abactinal 

 surface. Interbracbial arcs acute. 



The abactinal surface is beset with very short, rather broad, stumpy paxillse, the 

 crown composed of six to ten very short tapering spinelets, bi- or tri-dentate at the 

 extremity, and their bases imbedded in a membranous mass, which envelops the whole 

 basal part of the paxilla. The paxillse are widely spaced upon the disk, and numerous 

 large papulae occupy the interspaces. Along the rays the paxillse become much smaller 

 and more numerous. No definite order of arrangement is discernible, although a slight 

 tendency to lineal disposition may be made out along the sides of tLe rays. 



TLere is a single series of conspicuous marginal plates, on wLicL a tLin elevated keel 

 is developed, surmounted by a flattened comb of short robust spinelets, about ten to 

 twenty in each, resembling enlarged compressed paxillse, the long axis being placed at 

 right angles to the median line of the ray. The combs are widely spaced, and about 

 forty-two are present between the median interradial line and the extremity. I believe 

 these to be the infero-marginal plates ; and what I take to be the representatives of the 



