102 CRABS AND INSECTS. 
cocoon about itself (Fig. 117). The skin is now cast 
again, and the insect appears a short, seemingly lifeless 
pupa or chrysalis (Fig. 118), in which state 
is it remains a greater or less time, finally 
A shedding its skin and appearing a perfect 
s_ insect or zmago. This is known as a com- 
ee plete change. Others, 
as crickets, dragon-flies, 
grasshoppers (Fig. 119), 
pass through a partial 
Fic. 119.—Exampleof Change. Insectsare found 
WSs incomplete change everywhere ; far out at 
or metamorphosis. sea, as the Halobates (Fig. 
Us Young = grasshop- 3 . 
Fic. 118.— per: w, wing just 148), in deep caves, in hot 
Chrysalides. appearing. springs, and on the high- 
est glaciers, as the gla- 
cier-flea (Fig. 133). The bees and ants live seven years, 
some locusts thirteen or seventeen years, while the May- 
flies are born and die within twenty-four hours. In all, 
about 19,000 species of insects are known. 
Sub-Class I.—MaLacopopa. 
Peripatus (Peripatide).—The Peripatus is one of the 
simplest insects, having a long, soft, and cylindrical body, 
bearing from twenty-eight to sixty-six feet. Upon the 
head is a pair of jointed extensible antennz ; the feet are 
soft, and supplied with two claws. When alarmed, it in- 
stantaneously ejects a secretion that seems to crystallize in 
the air, forming a complete web in front. It is found in 
the West Indies, Panama, and Cape of Good Hope. 
Sus-Ciass I].—CrEntipeDes (Myriapoda). 
General Characteristics —Head free; thorax and abdo- 
men continuous; joints cylindrical, and often numbering 
two hundred, each bearing a pair of locomotive organs. 
