XXVm THE VOYAGE OF H.M.S. CHALLENGER. 



details in an outline sketch of our attempt to put together the scattered evidences and to 

 trace the lost records of the pedigree of life. 



The following is a summary of the classification I have adopted : — 



Class ASTEROIDEA. 



Sub-class EUASTEROIDEA, Sladen, 1886. 1 



Order I. PHANEROZONIA, Sladen, 1886. 



[Stenopneusia : Eurystroteria.] 



Euasteroidea with marginal plates large and highly developed in the adult. The 

 supero-marginal and the infero-marginal plates contingent and with their axes usually in 

 parallel planes. Papulas restricted to the abactinal area, circumscribed by the supero- 

 marginal plates. Ambulacral plates well spaced and usually broad, the development of 

 the ambulacral skeleton being retarded, or concurrent with that of the test generally. 

 Actinostomial ring Avith the adambulacral plates prominent. Pedicellarise valvate, fora- 

 minate, or excavate. 



Family I. ARCHASTERiDiE (Viguier, 1878), emend. Sladen, 1886. 



Phanerozonate Asterids with thick and massive marginal plates bearing spines or spini- 

 form papillae. Abactinal skeleton with simple spiniform spicules, with pseudo-paxillse, 

 or with true paxillae. Actinal interradial areas with plates bearing spinelets. Adam- 

 bulacral plates large and not compressed. Proctuchous. Pedicellariae frequently present. 

 No superambulacral plates. 



Subfamily 1. Paearchasteein^:, Sladen, 1886. 



Archasteridae with the papulae confined to a limited area at the base of the ray. 

 Marginal plates more or less alternate. Actinal intermediate plates absent or very few in 

 number. 



Genus 1. Pararchaster, Sladen. 



Genus 2. Pontaster, Sladen. 



Subfamily 2. Plutonasterisle, Sladen, 1886. 



Archasteridoe with the papulae distributed over the whole abactinal area. Marginal 

 plates opposite. Actinal intermediate plates well developed. No definite medio-radial 

 line of abactinal plates. 



Genus 1. Dy taster, Sladen. 



Genus 2. Plutonaster, Sladen. 

 Genus 3. Lonchotaster, Sladen. 



1 Date when the corresponding sheet of the descriptive portion of this work left my hands for press. 



