442 THE VOYAGE OF H.M.S. CHALLENGER. 
Family SoLastERID4&, Perrier, 1884. 
Notwithstanding the remarkable and in many respects archaic characters of the 
genera Solaster and Crossaster, they have until quite recently been classed with the 
Echinasteride. The discovery of deep-sea forms more or less closely allied has, however, 
excited closer attention, and in 1884 Perrier’ established the family Solasteride, which 
comprised Korethraster, Lophaster, Radiaster, Ctenaster, Solaster, and Crossaster. 
With this classification I fully concur, reserving only any expression of opinion as to 
the validity of the position of Radaster and Ctenaster in this family, in consequence of 
my want of knowledge of the structure of the forms in question. I have on these grounds 
not included them in the following table. 
I have added to the family two new genera, Peribolaster and Rhipidaster, the former 
approaching Korethraster in its affinities and the latter Crossaster. 
Synopsis of the Genera included in the Family SoLastERIDs. 
A. Armature of the adambulacral plates in two series at right angles to each 
other . : : . - . . SOLASTERINE. 
a. No actinal intermediate ‘lates Seu ‘the ray. 
a. With one series of well-developed marginal paxil. 
a. Abactinal structure reticulate. With widely spaced peni- 
cillate paxille. Papule numerous . : : Ql : Crossaster. 
8. Abactinal structure formed of stellate plates. With small 
closely crowded paxilla. Papulz single or few . 5 . Solaster. 
b. With two series of well-developed marginal paxille . 3 : Lophaster. . 
b. A continuous series of actinal intermediate plates along the ray, each of 
which bears an obliquely placed comb of spines . : : Rhipidaster. 
B. Armature of the adambulacral plates forming with that of the Ses ee 4 
mediate or infero-marginal plates a single transverse series . . KorerHrasterinz. 
a. Abactinal plates polygonal or rounded in outline.. The spines compos- 
ing the paxilliform tufts naked and free. 5 : 5 : : Korethraster. 
b. Abactinal plates cruciform; forming wide meshes. The spines com- 
posing the paxilliform tufts in membranous sacs which are united 
together in the interior of the group . : : 5 : : ¢ Peribolaster 
Subfamily SoLasterin#®, Sladen, 1888. 
Genus Crossaster, Miller and Troschel. 
Crossaster, Miiller and Troschel, Monatsber. d. k, preuss. Akad. d. Wiss. Berlin, 1840 (April), p. 103. 
The question of the validity of recognising Crossaster, Solaster, and Lophaster, as 
independent genera, has been so fully discussed by recent writers, that I do not propose 
to touch upon the subject further than to state that I maintain the three genera as 
1 Nouv. Archives Mus. Hist. Nat., 1884, 2e Série, t. vi. p. 164. 
