292 MANUAL OF NATUKAL HISTOET. 



fore-legs large, more or less completely didac- 

 tyle, the others elevated on each side of 

 thorax ; abdomen narrow ; body rather soft. 



27. FAMILY. True-Lobsters (Astacidae). Carapace 



elongated, beaked in front ; outer antennae 

 with a moveable lamina at their base ; outer 

 foot-jaws elongated ; fore-legs very large, end- 

 ing in thick didactyle pincers, second and 

 third pair with a small pincer, the others 

 monodactyle. 



28. FAMILY. Prawns (Crangonidae). Carapace 



rather depressed, slightly beaked in front; 

 eyes short, thick, free ; mandibles slender, 

 without palpi ; outer foot-jaws pediform ; 

 fore-legs ending in a flattened monodactyle 

 hand, with the finger rudimentary, second 

 pair with very small pincers, hind-legs 

 strong, monodactyle. 



29. FAMILY. Clicking-Shrimps (Alpheidae). Cara- 



pace rather compressed, shortly beaked in 

 front ; one pair of legs very large, and in 

 general ending in a strong didactyle hand, 

 two pairs of anterior legs didactyle, third 

 pair monodactyle, hind-legs robust, for swim- 

 ming or walking. 



30. FAMILY. Shrimps-Proper (Palaemonidas). Body 



laterally compressed ; carapace with a large 

 pointed serrated beak in front; first pair 

 of antennae often with three terminal fila- 

 ments ; legs all slender, the two first pair in 

 general didactyle, the three last monodactyle. 



