PRIMARY TYPES OF LARVAE. 5? 



name of grubs or maggots. The vulgar, also,, some- 

 times call these latter worms; but as this name implies 

 an affinity (of which there is none) to the common 

 earth-worm, and is likely., on other accounts, to lead to 

 error, we shall not introduce it. In this period of their 

 life, during which they eat voraciously, and cast their skins 

 several times, they continue a longer or shorter period ; 

 some only a few days or weeks others, several months 

 or years. In very many instances, particularly among 

 the Cokoptera and the Neuroptera, the period passed in 

 the larva state is much longer than that which the insect 

 enjoys when in adolescence. The food, also, which it 

 then consumes, is much more substantial in its nature, 

 and more abundant in quantity; nay, in some instances, 

 this is the only period when food of any description is 

 taken ; or, at least, the mouth of some perfect insects are 

 so small as to appear obsolete, and we may thence infer 

 they take little or no nourishment. Every one knows 

 how ravenously the common cabbage butterfly devours 

 the leaves of our garden vegetables ; and the appetite of 

 the silkworm is equally voracious: but when these in- 

 sects arrive at their perfect state, and are furnished with 

 wings, the first is merely supported by a little honey 

 sucked from a few flowers, while the silkworm moth 

 will live for weeks in confinement, without food, and 

 appear to die rather from the want of air and exercise 

 than from starvation. 



(53.) On the primary types of larva, that is, the 

 chief forms to which all their variations may be re- 

 ferred, a good deal has been written, and much more 

 remains for discovery. But we hear the student ex- 

 claim can it be possible that the system of repre- 

 sentation, of which so much has been said, should be so 

 universal, that vertebrate types can be traced among the 

 larvae of insects? and is it true that they follow each 

 other in the same succession ? The fact, however novel, 

 we venture to affirm, is perfectly true. Besides, it is 

 very clear that, unless such was actually the case, or, in 

 other wordsj unless all the groups of the Vertebraia 



