CLASS CRUSTACEA: OEDEB DECAPODA. 



231 



CRUSTACEA. 



Legs ten. 



Legs fouRiEXN. 



Legs lamellate. 



Legs aborted. 



Animals attached. 



Legs answering for jaws. 



Decapoda, 



Tetradecapoda, 



Pbyllopoda, 



SiphoDostoma, 



Giri-ipedia, 



Merostomata, 



Crab, Lobster. 

 Bea< h Flea, 

 Bi ine Shi imps. 

 Fish Lice. 

 Bamade. 

 Horseshoe Crab. 



ORDER DECAPODA. 



General Characteristics. — The Decapods (ten-footed) 

 have the anterior portion of the body covered with a single 

 piece called the carapax, the gills attached to the anterior 

 feet, and the eyes situated on movable peduncles. 



Mg. S9k. 



Astdeus flwviadlis, Cray-fish or Eiver Lobster. 



The Brachynra (short-tailed) have the abdomen small 

 and folded under the thorax. The anterior pair of feet are 

 furnished with pincers. The Crab (Fig. 393) is an example. 



The Macnira (long-tailed) have, as in the Lobster and 

 Cray-fish, the abdomen large and extended.* 



* The Fiddler Crah when alarmed holds up in front its big claw in a threatening way. 

 The Sand Crah runs to its hole so swiftly as to be overtaken with difficulty. The 



