126 ECHINODEEMATA. 



wise devour the Asterias glacialis. But they seem to labour under no 

 apprehension of their committing ravages among the oysters, or other 

 bivalves. 



Though the office of the spines be not very prominently shewn, they 

 are of some use in prehension or seizure. They can convey a whole load 

 of provender along with the animals contained in their shells, or employ a 

 vegetable cloke to serve as an ample covering. A specimen was taken in 

 July, when it persisted in rejecting food for some time. At length, be- 

 ing supplied with an entire mussel in the shell, it soon appeared bearing 

 this as a burden on its back. Next it was seen with a long worm which 

 chanced to be in the vessel, similarly secured, the long extremities hang- 

 ing over the sides; or it would cover itself, either wholly or partially, 

 with a portion of one of the littoral green fuci like a mantle. In accom- 

 plishing all this the spines are the active instruments. 



The animal can travel on its back by means of the spines and 

 suckers, and then the mouth appears in front. But this is an unnatural 

 position, though fixture and relaxation of these organs ensues, as pre- 

 viously described. 



It is the nature of this creature to carry every thing, whether use- 

 ful or useless, on its back. 



The Sea Urchin just referred to fed copiously afterwards. It was 

 delineated when a year in my possession, and still in progress of growth. 

 Plate XXXII. fig. 1, seen from below. 



The spines are deciduous, which is a singular feature in the history 

 of the animal, because reproduction seems concomitant on their loss. 

 Many were now beginning to fall from the preceding specimen, and 

 many more followed them, so that in the first week of August very few 

 remained. The tubercular spherical segments whereon they are sustained 

 then continue bare. 



The precise nature of neither, however, is sufficiently understood. 

 Some embarrassing i'acts accompany all the changes. 



The preceding Echinus did not seem to be distempered under its 

 losses ; it fed readily and profusely. Numerous low tubercles were exposed 

 to view in the month of August. But many new spines, some of them 



