MANUAL OF NATURAL HISTORY 289 



nal antennae very large ; hind-legs ambula- 

 tory, the same as the others. 



16. Family. — Shielded-Crabs (Dorippidae). Cara- 



pace depressed, quadrilateral, short behind, 

 often protected by shields of foreign bodies ; 

 external antennae very large ; fore-legs short, 

 hind-legs very short, not ambulatory, placed 

 above the others, and serving to secure the 

 adventitious shields. 



II. SUB-ORDER.— Varied-Tailed Decapods 

 (Anomoura.) 



Abdomen slightly developed, not serving for nata- 

 tion, sometimes folded under the body, sometimes ex- 

 tended, bearing appendages more or less developed. 



17. Family. — Sponge-Grabs (Dromiidae). Body glo- 



bular, front strongly recurved ; eyes short ; 

 outer foot-jaws enlarged, and operculiform ; 

 legs short and stout, fore-legs ending in 

 strong pincers, fifth pair raised above the 

 others on the sides of the carapace, and end- 

 ing in a hook. 



18. Family. — Stone-Crabs (Homolidae). Carapace 



spiny, beaked in front ; internal antennae ex- 

 posed ; foot-jaws pediform ; legs long, fifth 

 pair very short, not ambulatory. 



19. Family. — Frog-Crabs (Raninidae). Carapace 



ovate, narrowed in front ; eye-peduncles com- 

 posed of three moveable pieces ; internal an- 

 tennae exposed ; outer foot-jaws elongated, 

 not pediform ; fore-legs strongly compressed 



