REPORT ON THE ASTEROIDEA. 
a. Rays broad. Aperture-papille simple. 
1. Interbrachial arcs indented, defining broad lanceo- 
late rays. Spiracula numerous, large and con- 
spicuous. Spinelet-tips very prominent 
2. Interbrachial ares not indented; form pentagonoid. 
Spiracula few, small and inconspicuous. Spinelet- 
tips not prominent . . 
B. Rays attenuate. Aperture-papille comb- tiie: 
C. Adambulacral armature consisting of three spinelets. 
a. Muscular fibrous bands close, subdiffused, coherently reticulated. 
a, Paxille-crowns forming definite areas in relief. 
#, Paxillar elevations closely crowded. Spiracula uniformly 
distributed, not in lines. : ; & : 
B. Paxillar elevations widely spaced. ia confined to 
interspaces, arranged in lines 
b. Paxille-crowns not forming definite elevated areas. 
a Spines of the adambulacral armature partially webbed. 
Three pairs of secondary mouth-spines : 
B. Spines of the adambulacral armature not webbed. Two 
pairs of secondary mouth-spines. 
1. Meshes of supradorsal membrane irregular and not 
uniform. Spines of the adambulacral armature 
unequal . : . . c 
2. Meshes of supradorsal oven small and aioe 
Spines of the adambulacral armature equal - 
b. Muscular fibrous bands fine, definite, widely spaced, simply intercrossing. 
a. Supradorsal membrane with granular bodies . ° ° 
6. Supradorsal membrane devoid of granular bodies. 
a, Spines of the adambulacral armature long and needle-shaped 
B. Spines of the adambulacral armature short and compressed. 
1. Muscular fibres very numerous in supradorsal mem- 
brane. Webof the actinal floor with cross muscular 
fibres. Longest actino-lateral spine the 12th 
2. Muscular fibres not very numerous in supradorsal 
No muscular fibres in the web of the 
actinal floor, Longest actino-lateral spine the 17th 
D. Adambulacral armature consisting of more than three spinelets. 
a. Three or four spinelets in the adambulacral armature. Aperture-papille 
five to seven rayed, comb-like, large. One pair of secondary mouth-spines 
b. Three to five spinelets in the adambulacral armature. Aperture-papille 
simple, small and dumpy. Two or three pairs of secondary mouth-spines . 
membrane. 
vicariua. 
pellucidus. 
infernalis. 
calatus. 
crucifer. 
anomalus. 
latebrosus. 
porosissimus. 
grantferus. 
geometricus, 
pullatus. 
membranaceus. 
coccinatus. 
precoquis. 
1. Hymenaster nobilis, Wyville Thomson (Pl. LXXXVII. figs. 1-8). 
Hymenaster nobilis, Wyville Thomson, 1876, Journ? Linn. Soc. Lond. (Zool.), vol. xiii. p. 73, fig. 11 ; 
Voy. of Challenger, Atlantic, vol. 11. p. 238, fig. 48. 
495 
Marginal contour pentagonal, interbrachial ares very slightly indented, the margin 
forming a continuous curve of small degree from tip to tip. Rays not produced, and 
tapering very slightly beyond the natural angle of a pentagon. 
The minor radius js in 
