898 INVERTEBRATES. 



The Scorpion. — These formidable creatares inhabi. most 

 of the hotter parts of the globe. They are quite as pugnacious 

 as the spiders, and if several are placed in one box, they will fight 

 until few survive, who immediately devour their fallen foes. 



The maxillae of the Scorpion are developed into large claws, 

 like those of the lobster. With these, the Scorpion seizes its prey, 

 and while holding it pierces it with its sting, which is situated at 

 the extremity of its tail. The tail is composed of six joints, ren- 

 dering it very flexible. 



The sting of this creature is exceedingly painful, and with 

 some persons dangerous"; indeed, the sting of the large black 

 Scorpion of Ceylon is said to cause death. 



CHAPTER XVII. 



DIVISION II.— INVERTEBRATES. 



CLASS VI.— CRUSTACEOUS ANIMALS. CLASS VII.— MOLLUSKS. 



The Crustacea have articulated limbs, antennae and jaws, 

 very similar to those of insects, among which they have sometimes 

 been included; but they differ from the latter in their respiratory 

 apparatus — breathing by means of gills, and hav-lMg a regular 

 double circulation. After passing through the gills, the blood is 

 collected into one large vessel, which distributes it through the 

 entire body. Returning, it is collected into another vessel situated 

 near the back, performing in some respects the ofSce of a ventricle, 

 and is thence again sent to the gills. 



The animals of this class are enveloped in a tolerably thick, 

 firm shell, which shelters and protects the soft parts from injury, 

 besides serving as instruments of motion. This shell being inca- 

 pable of growth, it is occasionally changed, to accommodate the' 

 increasing size of the animal ; at which times the body being in a 

 soft and defencolcss state, the animal usually conceals itself until 



