THE WONDERS OF THE SHOEE. 119 



are tliose seemingly identical gills, if you come to 

 examine them under the microscope, having to 

 oxygenate fluids of a very different and more com- 

 plicated kind ; and, moreover, the Cucumaria's gills 

 were put round his mouth ; the Doris's feathers round 

 the other extremity ; that grey Eolis's, again, are simple 

 clubs, scattered over his whole back, and in each of 

 his nudibranch congeners these same gills take some 

 new and fantastic form ; in Melibaea those clubs are 

 covered with warts ; in Scyllsea, with tufted bouquets ; 

 in the beautiful Antiopa they are transparent bags ; 

 and in many other English species they take every 

 conceivable form of leaf, tree, flower, and branch, 

 bedecked with every colour of the rainbow, as you 

 may see them depicted in Messrs. Alder and Han- 

 cock's unrivalled Monograph on the Nudibranch 

 MoUusca. 



And, now, worshipper of final causes and the mere 

 useful in nature, answer but one question, — Why 

 this prodigal variety? All these Nudibranchs live 

 in much the same way : why would not the same 

 mould have done for them all? And why, again, 



