THE PURPLE-TIPPED SEA-URCHIN. 



723 



After inquiry, it proves that these divers were engaged in fishing for Sea-urchins, 

 which are especially valuable just before they deposit their eggs, the roe, as the ag- 

 gregate egg masses are termed, being large and in as much repute as the " soft roe " 

 of the herring. 



These Sea-urchins are fond of burrowing into the sand, an operation which is con- 

 ducted mostly by help of the movable spines. They will sink themselves entirely out 

 of sight, but not without leaving a slight funnel-shaped depression in the sand, which 

 is sufficient to guide a practised eye to their hiding-place. 



THE species which is shown in the accompanying illustration is given, not so much 

 for the sake of its own beauty or for any peculiarity of form, as to exhibit the structure 

 and habits of the Echinidae in general. The PURPLE-TIPPED SEA-URCHIN is here 





PURPLE-TIPPED SEA-URCHIN.-Ec/j/nus mUlaria. 



shown in many attitudes. The specimens are shown as they appear in an aquarium, 

 and the drawings were taken from life. 



On the upper part of the illustration is seen a Sea-urchin crawling up the glass front 

 of the aquarium, and exhibiting the beautiful suckers, or ambulacra, by means of which 

 it is enabled to walk. The expanded tips of the suckers are especially to be noted. Two 

 of these suckers are seen plan ted on the rock, for the purpose of exhibiting the beautiful 

 construction of their extremities. These are, of course, magnified. Another specimen is 

 seen on the right hand, climbing up a rock, and carrying with it a number of pebbles, 

 which act as a kind of shield or protection. The specimen from which this drawing was 

 taken was in the habit of climbing to the upper edge of a living modiola, and there 

 remaining, with its stony umbrella held over its body. The pebbles are held by the 

 ambulacra, which attach themselves just as if they were employed in moving the whole 

 body. Sometimes the Sea-Urchin will collect together such a number of stones and 



