280 
THE OCEAN WORLD. 
The family of Ophiuradco is divided into two great sections : that oi 
the Ophiura, which comprehends several genera, amongst others that 
which gives its name to the family, and that of the Euryalina or 
Asterophytes. 
The family of Ophiuradm constitute a group distinguished by their 
five simple, articulated, very mobile, and non-ramified arms, which 
Fig. no. Ophiocoma Russei (Lutken), natural size. 
are attached to a small disk or shield plate, with flexible thread-hk e 
cirri between the rays. Ophiura ncitta is very common, and has bee* 1 
known from very early times in European seas. It is of a greenish 
colour, with transverse bands, which become more obscure upon th e 
arms as the distance from the disk increases. This disk is from six to 
seven-eighths of an inch in size, the upper part covered with uneqR a 
plates, in shape like tiles ; the arms are four times the length of fh e 
