DESCRIPTION OF GENERA AND SPECIES. 



Class ASTEROIDEA. 



Sub-class EUASTEROIDEA, Sladen, 1886. 



Order PHANEROZONIA, Sladen, 1886. 



Family Archasterid^; (Viguier, 1878), emend. Sladen, 1886. 



This family was first established by Viguier, 1 and comprised in his estimation the 

 single genus Archaster of Muller and Troschel, to which at that date about twelve species 

 were referred. Viguier, however, appears to have only had the opportunity of examining 

 specimens of three or four of these, and the two species, Archaster typicus, M. and T., 

 and Archaster angulatus, M. and T., were the forms taken by him as typical, and from the 

 study of which the characters of the family were formulated. The genus Archaster was 

 first established by Muller and Troschel, 2 for the reception of the two species named by 

 them Archaster typicus and Archaster hesperus. Other species were subsequently 

 referred to the same genus, though many are so widely different that latterly Archaster 

 might well lay claim to be considered as the "refuge for the destitute ! " It is scarcely 

 exaggeration to say that most of the long-rayed Phanerozonate Asterids that could not 

 immediately be ranked either as Pentagonaster on the one hand or Astropecten on the 

 other, were at once set down as Archaster! Amongst the Starfishes thus disposed of 

 were several deep-water forms, and a number of those recently discovered were temporarily 

 relegated in like manner to Archaster at the time they were taken, and before the species 

 were systematically described. In this way Archaster, and consequently the Archasteridas, 

 have come to be spoken of as characteristic abyssal forms. 



I have considered it desirable, for reasons explained in their proper place, to divide 

 the species that have hitherto been called Archaster into several genera, and some of 

 these it has been necessary, on account of their structure, to remove from the family 

 Archasteridse altogether. The establishment of several new genera has likewise been 

 requisite for the reception of new types. Amongst the series of allied genera that 

 constitute in my classification the family Archasteridse, the genus Archaster as now 

 limited is in many respects a very divergent form, and is certainly not the one which I 



1 Archives de Zool. exper., 1878, t. vii. p. 235. 



2 Monatsber. d. L Akad, d. Wiss. Berlin, April 1840, p. 104. 



(ZOOL. CHALL. EXP. — PAET LI. — 1887.) 1 



