EASTERN UNITED STATES. 21 



two feelers, called palpi, the outer composed of several 

 joints, the inner of only one. Between and partly below 

 or back of the maxillae is the labium, or under lip, being 

 more like the maxillae than like the upper lip. This 

 bears on each side at the tip a small jointed appendage : 

 these appendages are termed the labial palpi. Between 

 these is another appendage, tubular, which is similar to 

 the spinneret of the spider, and from which the cater- 

 pillar spins a web over smooth surfaces as a support for 

 its feet in walking, and the silk it fastens its feet to in 

 moulting and in changing to a chrysalis. Back of the 

 jaws, somewhat in the form of a crescent, are the eyes, 

 or ocelli, five or six on each side. 



The bodies of different caterpillars differ greatly in 

 their external covering as well as in shape. Some ap- 

 pear to be naked, but even these are covered with a 

 delicate pile ; others have simple or compound spines or 

 tubercles, usually arranged in longitudinal rows with a 

 definite number to each joint, generally beginning with 

 joint three, or the second thoracic segment. 



Usually the larvae of butterflies are cylindrical, in some 

 a little enlarged at or near the middle; in others, as 

 in some Papilios, the thoracic segments are enlarged, 

 and at times assume shapes peculiarly their own. In 

 such cases the head is often smaller than the succeeding 

 joints, and when at rest is drawn back, as it were, into 

 the joint behind. In others the second segment is 

 smaller than the head, as with many of the Hesperians. 



Most butterfly larvae have the thoracic and abdominal 

 legs as given at first, but in some, as the Lycaenidae, the 

 prolegs' are very small, and the caterpillar seems to glide 

 over surfaces instead of walking, the under side being 



