92 POLYPI. 



a needle, or very fine wire is introduced into the perforation, 

 after it has been filled with cement. The shell of the Echinus 

 must now be filled with melted bees'-wax : care is taken to stop 

 up all the openings, while in the act of pouring in the melted 

 wax. When the wax has cooled, a hole is bored in each tu- 

 bercle, for the reception of the needle, which must first be 

 warmed at a lighted candle, and, the wax cooling, holds the 

 needle firmly in its place. 



A better plan, however, than the above is, to use very fine 

 wire, which ought to be bent as nearly at right angles as pos 

 sible, before being introduced ; and, having filled up all the 

 vacancies of one side in this way (always leaving as much out- 

 side as will fit into the perforation made in the base of the 

 spine) ; pour in some cement, made as thin as it will flow 

 easily, and then set it aside to dry. Repeat the same operation 

 with the other side ; and, when dry, the spines may be placed 

 on the projecting wires with cement, as above directed, The 

 wire which is left outside should be roughened with a file here 

 and there, previous to its being inserted, so that it may the 

 better retain its hold in the cement. 



CLASS XI ENTOZOA ; AND CLASS XII. 

 ACALEPHA. 



The animals of these classes are best preserved in spirits, 

 and indeed there is no other manner of setting them up. We 

 have made attempts to preserve worms, by removing the in- 

 testinal canal and oviducts, and injecting the skin with wax, 

 but we never succeeded in rendering them natural in point of 

 shape. We have also tried the same method with different 

 species of Actinea, or Sea Suckers, but the same unsuccessful 

 results have attended them. 



CLASS XIII. POLYPI. 



Zoophites, or Corals, generally live in families or congre- 

 gated masses. Their axis is of a horny consistence, generally 

 hard, and disposed in layers ; tlieir surface is usually fur- 



