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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 85 



the spiracles are really paratergal sclerotizations that have secondarily 

 united with the sterna. 



In the larvae of holometabolous insects there is usually a more 

 or less distinct groove extending along each side of the abdomen 

 below the line of the spiracles (fig. 3 A, B, C, a-a), which is continued 

 upon the thoracic region above the regions of the pleural, or subcoxal, 

 sclerites, when the latter are present (B, C, Scx^). This groove, 

 therefore, evidently marks the division between the dorsal and pleural 

 areas of the abdominal segments, and may be termed the dprso- 



FiG. 3. — External structure of the abdomen in holometabolous larvae. 



A, larva of Carpocapsa pomonella, showing the dorso-pleural fold {a-a) sepa- 

 rating the dorsum from the subcoxal areas in both the thorax and the abdomen. 



B, larva of SUpha obscura, with series of paratergal sclerites (patg) above 

 dorso-pleural fold, and series of pleural subcoxal sclerites (Sex) below fold. 



C, larva of Ptcronldea ribesii, showing same structure as in B. 



pleural groove. Sclerites or lobes of the body wall lying immediately 

 above this groove, then, belong to the dorsum, and may be called 

 paratergites (fig. 3 B, patg), but not " pleurites " or " epipleurites." 

 Latero-ventral plates or lobes lying below the tergo-pleural groove 

 are properly termed abdominal pleura (B, Sex) if it is clear by their 

 position or by the presence of appendicular organs upon them that 

 they are the equivalents of the thoracic subcoxal pleura (Scv-s). It 

 is convenient, however, to extend the term " pleurites " to any lateral 

 sclerites situated ventrad of the dorso-pleural groove, or below the 

 line of the spiracles, though such sclerites may be evidently secondary 

 sclerotizations of this region (fig. 24 D, ipl, 2pl, etc.). But if there is 



