Q2 CLASS INSECTA. 



of the larva, has only the appearance of a small egg-shell. 

 It is a sort of capsula or case in which the animal is enclosed. 

 {Pupa coarctata, Lin.) 



Many larvae, before they pass into the nymph state, pre- 

 pare for themselves with silk, which they draw from within, 

 or with other materials which they combine together, a shell 

 in which they enclose themselves. The perfect insect issues 

 from the nymph, through a cleft or division made on the 

 back of the corslet. In the nymphse of flies one of the ex- 

 tremities is detached, coming off like a cap for the passage of 

 the insect. 



The larvae and the nymphse of insects, which undergo but a 

 semi-metamorphosis, differ from these insects in a perfect 

 state only with relation to the wings. The other external 

 organs are identical. But in the complete metamorphosis, 

 the form of the body of the larva has no invariable relation 

 with that which these insects are destined to possess in this 

 perfect state. It is usually more elongated ; the head is 

 often very different both in its consistence and figure ; it has 

 only the rudiments of antennas, or wants them altogether, 

 and never exhibits the complicated eyes. 



In the organs of manducation there is still greater dis- 

 parity, as may be seen by comparing the mouth of a cater- 

 pillar with that of a butterfly, the mouth of the larva of a 

 fly with that of the completely developed insect. 



Many of these larvae have no feet ; others, such as the 

 caterpillar, have many, but which, with the exception of the 

 first six, are all membranous, and have no claws at the end. 

 Some insects, as the ephemera, exhibit in their metamor- 

 phosis a singular exception to the rest. When arrived at the 

 perfect state, they are again stripped of their wings. 



The insects which compose our first three orders preserve 

 during their existence the form which they had at birth. In 

 the myriapods, however, we perceive a faint sketch of a meta- 



