CHAPTER VII 



THE CRUSTACEA. 



ALTHOUGH these are next in the ascending scale the jump 

 seems a big one. We now encounter high organisation, 

 and for the first time to our senses the manifestation 

 of conscious intelligence. 



The Crustacea are differently divided by different 

 authorities, but most place them as follows : 



1. Epizoa. Small crustaceans of parasitic habit, of 

 which Lernea, a parasite of the sprat, is the type. (This 

 definition is poor, as many of the higher divisions are 

 also parasitic.) 



2. Cinipedia.The ship -barnacle and its allies. 



3. Entomostraca. Small crustaceans, of which the 

 ; ' Water-flea " of our ponds and ditches is the type. 



4. Malacostraca. All the others viz. the sand- 

 hoppers, gammarids. shrimps, lobsters, and crabs. 



The first division we will pass over, there is nothing in 

 it of interest except to the specialist, and proceed to the 

 Cirripedia. 



The " Ship-barnacle " (Lepas anatifera) is of very great 

 interest, and we shall consider it at some length. 



The photograph (Fig. 44) gives a good idea of its out- 

 ward form. 



The place in nature of this curious crustacean was 

 formerly a matter of great perplexity. Some of the old 

 writers thought it was a bird ! or at least a developmental 

 stage of one viz, the Bemide goose. In fact, its scientific 



110 



