CLASS CKUSTACEA: ORDER DECAPODA. 



231 



CRUSTACEA. 



LEGS TEN. 

 LEGS FOURTEEN. 

 LEGS LAMELLATE. 

 LEGS ABORTED. 

 ANIMALS ATTACHED. 



LEGS ANSWERING FOR JAWS. 



Decapoda, 



Tetradecapoda, 



Phyllopoda, 



Siphonostoma, 



Cirripedia, 



Merostomata, 



Crab, Lobster. 

 Been h Flea. 

 Brine Shrimps. 

 Fish Lice. 

 Barnade. 

 Horse-shoe Crab. 



ORDER DECAPODA. 



General Characteristics. The Decapods (ten-footed) 

 nave 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. 



Fig. 39k. 



Astdcus Jtuviafilis, Cray-fish or River Lobster. 



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

 Cray-fish, the abdomen large and extended.* 



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

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



