20 OPH1URID.E. 



longation of the digestive organs. The stomach is a sac 

 with one aperture, its walls externally covered with 

 vihratile cilia. The ovaries are not branched ; they are 

 placed near the arms, and open by orifices near the mouth, 

 between the origins of the arms. Their investing mem- 

 brane is also ciliated ; but on the rest of the body and 

 arms no cilia exist — hence we may conclude there is no 

 separate respiratory system. 



The Ophiuridse are always regularly radiate, and they 

 seldom vary in the number of their parts. With them 

 the number five is absolute. Colour and proportions are 

 the subjects of variation in this order. Generic characters 

 among them are founded on the simplicity or complexity 

 of the arms, the mode of their insertion, and on the forms 

 of the plates which separate their origins beneath. The 

 sources of specific character are derived from the spines 

 and scales of the body and arms, and the proportions of 

 arms and disk. Colour is variable in all the known 

 species. 



What I take to be the nervous system will be found 

 described under the account of Ophiocoma bellis. There 

 is no appearance of ocular spots in the animals of this 

 order. 



The Ophiurido' are very generally distributed through 

 the seas of our earth, both of its northern and southern 

 hemispheres. The species do not present such wide 

 ranges as the true Starfishes. They are more affected 

 by climatal causes, which seem to influence their size, 

 they being largest in the tropical seas. In our own seas 

 they are very abundant, and are among the most curious 

 and beautiful game pursued by the dredger. Among the 

 relics of the Radiata of the primaeval seas we find several 

 species of Ophinrida\ No extreme change has taken place 



