400 



PHYLUM ARTHROPODA 



ametabolic and hemimetabolic forms the larva is somewhat 

 Hke one of the lowly Thysanuran insects {Campodea)^ and is 

 therefore called campodeiform. It has the regions of the 

 body well defined, three pairs of locomotor thoracic limbs, 

 and biting or sucking mouth-parts, {b) The other type 

 is worm-like or cruciform, e.g. the caterpillars of Lepidop- 



FiG. 222. — A typical caterpillar. — From a Specimen. 



A., The small antennse ; E., the simple eyes ; /., future prothoracic segment, 

 with first stigma and first pair of jointed clawed legs ; //. and ///., 

 second and third pairs of jointed clawed legs ; i, first pro-leg on the 

 segment corresponding to the third abdominal ; ST., seventh stigma 

 on the segment corresponding to the seventh abdominal ; 8, the 

 eighth stigma ; H., a dorsal " horn " on the eighth abdominal segment ; 

 5, the fifth pro-leg on the tenth abdominal segment, the ninth being 

 telescoped. In reality, at this stage, there are only two regions in the 

 body — the head and the trunk ; but the first three segments after 

 the head correspond to the future thorax, and the subsequent ten to 

 the future abdomen. 



tera (Fig. 222), with distinct head and limbs ; the more 

 modified grubs of bees, etc., with distinct head, but without 

 limbs ; and the degenerate maggots of flies (Fig. 223, A), 

 etc., not only limbless, but with an ill-defined head, A 

 typical caterpillar has a cylindrical body often " hairy," a 

 distinct hard head, simple eyes, small antennae, mouth- 

 parts suited for biting, three pairs of jointed clawed thoracic 

 limbs (corresponding to those of the butterfly), and four or 



