THE CATKKlMLLAi:: sTRUCTniE OF THE F.ODY. H 



upon tliis sciiincul lliaii 111)011 iuiy otlier ; and like tlic first segment it seldom 

 if ever hears a[)[)eiida<;'es of (piite the same eharaeter as the rest of the hody. 

 A^'itll these exceptions, however (and the presence or ahsence of legs and 

 spiracles) the joints of the hody arc very similar to each other. They may 

 he di\ ided into tlioracic and ahdominal according as they helong to these 

 [irospective regions, the former hearing each a pair of legs, the hitter hear- 

 ing prolegs only, and always on the third to the sixth and on the tenth 

 ahdominal segments. 



The legs (87:1-")) are five-jointed, the hasal two joints usually large and 

 fiesliv, the apical three generally coriaceous or horny, longer than hroad, 

 the last armed with a simple, small, hent or curved, often heeled claw. 

 The prolegs (86 :'27,81 ; 87 :21) consist of two very large, fleshy, short 

 and stout joints, the apical hearing on the inner side of its tip a pair of 

 thickened pads moving laterally, the outer and sometimes the inner of which 

 bears a strongly curving row of minute hooks ; the ventral prolegs are 

 directed downward, the anal pair or that of the tenth segment both down- 

 ward and hack\\'ard ; the latter arc also a little larger, and the pad provided 

 more abundantly with booklets. The long basal portion of the booklets is 

 lightly inil)edded in the skin and the exserted portion is slender, strongly 

 curved and hooked, the hook sometimes })lunt and sometimes ]iointed ; they 

 are sometimes arranged in single, sometimes in double or triple rows, and 

 apparently can be extended somewhat at will ; the tip of the foot between 

 the pads may be so inflated, especially in the Papilioninae and Hesperidae, 

 as to bring the rows of hooks outside and thus the pads can be opened or 

 shut at jileasure, the animal cling with great tenacity to any object upon 

 which it is standing, and also readily disengage itself. The hooks are 

 always numerous, thickly crowded, and increase in number with age ; 

 sometimes as many as one hundred are found on each foot. 



Breathing pores or spiracles, sometimes called stigmata, occur only on 

 the first thoracic and first to the eighth abdominal segments* ; they are 

 situated a little below the middle of the sides, in the centre or slightly in 

 ad\ance of the centre of the segments, and consist of straight slits trans- 

 ^■crse to the body, surrounded by a thickened lip, the outer margin of 

 which is usually oval and frequently raised ; the spiracles of the first tho- 

 racic and eighth abdominal segments are frequently higher than the rest, 

 especially in the Lycaeninae and Hesperidae, and also often larger. 



*In some Lepidoptera, as in the young cat- Algernon Coolidge of England, through Rev. 

 erpillar of ranijjhihi inandan.siiiraclesniay be Mr. Hollin.s of Exeter. On drawing Dr. Pack- 

 found on the second and third thoracic seg- ard's notice to the subject he discovered the 

 nieuts; and in many others there arc false spir- chistered tracheal tubes though without ex- 

 acles, having no connection with the air tubes ternal sign of spiracles in the larvae of one of 

 of the interior, whicli ramify in these seg- the Sphingidae and in Platysamia cecropia 

 nients, as will be seen, quite as in others. My (Am. nat., viii : 531). I believe these last may 

 attention was lirst directed to the occasional be found in all Lepidoptera. In the perfect 

 presence of true spiracles on the hinder tho- insect, as we shall see, there is a uiesothoracic 

 racic segments of lepidopterous larvae In- Dr. spiracle. 



