60 INTRODUCTION TO ZOOLOGY. 



injustice to the reader not to present him with the portrait 

 which that gentleman has furnished: "It is the wonderful 

 power which the Luidia possesses, not merely of casting away 

 its arms entire, but of breaking them voluntarily into little 

 pieces with great rapidity, which approximates it to the 

 Ophiurce. This faculty renders the preservation of a perfect 

 specimen a very difficult matter. The first time I ever took 

 one of these creatures I succeeded in getting it into the boat 

 entire. Never having seen one before, and quite unconscious 

 of its suicidal powers, I spread it out on a rowing bench, the 

 better to admire its form and colours. On attempting to remove 

 it for preservation, to my horror and disappointment I found 

 only an assemblage of rejected members. My conservative 

 endeavours were all neutralized by its destructive exertions, 

 and it is now badly represented in my cabinet by an armless 

 disc and a discless arm. Next time I went to dredge on the 

 same spot, determined not to be cheated out of a specimen in 

 such a way a second time, I brought with me a bucket of cold 

 fresh water, to which article Star-fishes have a great anti- 

 pathy. As I expected, a Luidia came up in the dredge, a 

 most gorgeous specimen. As it does not generally break up 

 before it is raised above the surface of the sea, cautiously and 

 anxiously I sank my bucket to a level with the dredge's 

 mouth, and proceeded, in the most gentle manner, to introduce 

 Luidia to the purer element. Whether the cold air was too 

 much for him, or the sight of the bucket too terrific, I know 

 not ; but in a moment he proceeded to dissolve his corporation, 

 and at every mesh of the dredge his fragments were seen 

 escaping. In despair I grasped at the largest, and brought 

 up the extremity of an arm with its terminating eye, the 

 spinous eyelid of which opened and closed with something 

 exceedingly like a wink of derision." 



The members of the fourth family, that of the Sea-urchins 

 (Fig. 33) are furnished with spines, and, from the resem- 

 blance in this respect to the Hedgehog (echinus), the family 

 bears the name Echinidce. Here the arms have disappeared, 

 and the form has become more or less rounded, according to 

 the species. The spines do not grow from the "shell," or, 

 to use a more correct term, the integument, as thorns do on 

 the branches of the common hawthorn. They are attached 

 to tubercles, and move upon them in the manner of so many 

 ball-and-socket joints. The Sea-urchins are also furnished 



