VIII 



ECHINODERMATA SYSTEMATIC REVIEW 



301 



Order 2. Euryalse. 



Arms simple or branched, can be rolled up vertically towards the mouth. Only 

 rudimentary shields are found below the soft but thick outer integument. Without 

 spines. In forms with unbranched arms there are usually 5 buccal shields, one of 

 which is the madreporitic plate. Most of the forms with branched arms have no 



FIG. 246. Astrophyton LincM (Miiller a 



}Ch.el), from the oral side (original). 



distinct bnccal plates. There is then either a single madreporite in an oral inter- 

 brachial area or else there are 5 interbrachial madreporites. 



Single Fam. Astrophytidse : Astrophyton (Fig. 246), Gorgonocephalus, Euryale, 

 Trichaster (arms slightly and only at their tips, dichotomously branched), Astroclon 

 (the same), Astrocnida (the same), Astroporpa (arms undivided), Astrogomphus (the 

 same), Astrochcle (the same), Astrotoma (the same), Astroschema (the same), Ophio- 

 creas (the same), etc. 1 



1 For a more recent classification of Opliiuroidea, see F. J. Bell, Proc. Zool. Soc. 

 London, 1892, pp. 175-183. 



