ANALYTCAL INDEX. 



275 



CHAPTER IL— continued. 



Description, . . . • • 



Plate XXIX., explained, 

 Miscellaneous observations, 



COMATULA BARBATA, 



This animal nearly allied to the Ophiura, 



Form, organs, and habits. 



Liable to great mutilation, ... 



Food unknown, . . . • 



Not so rare in Orkney as elsewhere in Scotland, 



Plate XXX., explained, 



Echinus, the Sea Urchin, 



Observations of reputable authors imperfect, 



Insufficiency of Artists, &c.. 



§ 1 



PAGE lis 

 ib. 



ib. 

 120 



ib. 

 ib. 

 ib. 



121 

 ib. 

 ib. 

 ib. 

 ib. 

 122 



Echinus spil^ra, . . . • • 



Size, organs, peculiarities, and habits. 



Spines of use in prehension or seizure. 



Can travel on its back by means of the spines and suckers. 



Carries everything useful or useless on its back, 



The spines are deciduous, but reproduction restores them. 



Divested of the spines the shell resembles an orange. 



Colour darkens with age, . . • • • 



Shell about the sixteenth of an inch thick. 



Planked like the hull of a vessel, . . . • 



Orifice above surrounded internally with the ovarium. 



If uninjured is not of difficult preservation. 



Natural propensity to destroy, . . . • 



Reputed to have been used as food by the ancients, 



Said to have been formerly brought to the Edinburgh Market for 



the sake of the roe, . . • • • 



One species denominated Echinus edulis, 



Animal described, ...••• 



Pedicellarias cover the Echinus in thousands. 

 The head separates from the stalk, . . • • 



Not separate and independent parasites, 

 Plates XXXI., XXXII., explained. 



123 

 ib. 

 I'JG 

 ib. 

 ib. 

 ib. 

 127 

 128 

 ib. 

 ib. 

 ib. 

 129 

 ib. 

 ib. 



ib. 

 ib. 

 130 

 131 

 132 

 ib. 

 ib. 



§ 2. Echinus (Spantangus purpureus), . • • 133 



Another kind of Echinus, . . • • . ib. 



Very different in form, and less familiar to naturalists, . ib. 



Called Man's face, and Monkey face, by the Scottish fishermen, ib. 



Belongs to deep water, and is often permanently buried in the sand, ib. 



