104 CRUSTACEA. 



in general very much developed, and always composed of 

 seven joints ; the eyes are affixed upon moveable footstalks; 

 the internal antennae are always terminated by two or three 

 filaments ; the organs of the mouth are formed nearly as in 

 the Decapods (lobsters, &c.), but the foot-jaws have the form 

 of large claw-like legs, those of the second pair (or first pair 

 of leg-like organs) very often much larger than the other 

 legs, and used in prehension. 



These Crustacea are essentially marine, and die as soon as they 

 are taken out of the water ; they are generally natives of tropical 

 seas, not extending beyond the temperate zones. Their economy 

 is not yet ascertained, but it is evident that those which are pro- 

 vided mth claws {Squilla) employ them in seizing their prey. 

 These species generally frequent very deep water, but the others, 

 destitute of s^-imming apparatus, and the body very broad and 

 slender, are generally found at the surface of the ocean, where 

 they float about with very httle individual motion. 



There are two sections, or rather families, in this order, 

 named Unipeltata and Bipeltata, having respectively for their 

 types the genera Squilla and Phyllosoma. 



In the SquillidcB the body is long and semi-cylindi-ic, 

 somewhat resembhng that of a lobster, being arched above 

 and flat beneath, the last segment rounded and spined, or 

 toothed, on its posterior margin ; the interior antennae have 

 three filaments, the exterior single, but covered at the base 

 by a broad scale ; the thoracic shield is broad, and somewhat 

 depressed ; the first pair of legs, or rather leg-hke organs, 

 are long and strong, and formed for powerful prehension, 

 the last joint shutting upon the preceding, with strong spines, 

 in the same manner as the fore-leg of one of the Mantidce. 

 The species are somewhat numerous. They are chiefly in- 

 habitants of the seas of warm chmates, but one or two of the ' 

 species have occasionally been taken upon our own coasts ; 

 some of them are of considerable size, and are employed for 

 food by the inhabitants of the Mediterranean, in the same 



