170 A CRUSTACEAN CURIOSITY. 



Unable to escape, it counterfeits death, and remains per- 

 fectly immovable. 



Now examine it. It has fourteen feet, symmetrically arranged 

 in couples ; their size perceptibly increases from the first to the 

 last. When the animal is at rest, they are coiled inside, so as 

 to form an angle whose opening faces the medial line. But 

 here is something much more curious ; its body, which does 

 not possess the vestige of a wing, is also without those seg- 

 ments which would divide it visibly, as in the case of insects, 

 into head, thorax, and abdomen ; but is composed of rings, 

 hard and scaly, like those of a shrimp. 



Can it be a crustacean ? 



Yes ; the animal you hold in your hand, and which every- 

 body knew by the name of wood-louse long before our 

 naturalists knew how to classify it, belongs to the great animal 

 division of the Articulata, which, instead of having their 

 skeleton inside the body, like the Vertebrates, have it ex- 

 ternally. The Crustacea form a class of this division, to which 

 also belong the Insects, the Arachnida, and the Myriapoda. 



Let us continue to anatomise our crustacean. 



In front of its first ring (a transversal segment) you see a 

 little black head, with two lateral bead-like eyes, and a couple 

 of antennae. The latter are each composed of three joints, 

 which are extremely mobile; their base is covered by the 

 edges of the sloping head. The most conspicuous rings of 

 the body are seven in number; their lateral borders are 

 pointed in front, and rounded behind. But, if you look 

 closely, you will see some other rings, a little less projecting 



