SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 



on the visceral region of the abdomen it extends below the series 

 of spiracles (fig. i C) and above the limb bases where the latter 

 are present (fig. 2 C) ; and finally it runs out above the bases of the 

 gonopods, pygopods, and uropods, or cerci (figs, i C, 2D, E, F). 



The pleuro-ventral line (fig. i B, h-h) begins anteriorly between the 

 bases of the gnathopods and the ventral wall of the head (fig. 2 A) ; 

 on the thorax (figs, i C, 2 B) it separates the leg bases from the true 

 venter ; on the abdomen it runs ventrad or mesad of the limb bases, 



Stn LB 



"~~iGon 

 b ,' LB LB XStn 

 VUistn 



Fig. I.— Diagrams showing the lengthwise division of the body surface of 

 an insect into dorsal, ventral, and podial regions by the series of limb bases along 

 the sides. 



A, cross section, B, lateral view, of theoretically primitive condition in which 

 the podial, or pleural, region of the body (P) consists of the segmental areas 

 containing the limb bases {LB), the dorsum of the region (D) above the dorso- 

 pleural line (a-a), and the venter (F) of that below the pleuro-ventral line {b-b). 



C, generalized structure of thorax and abdomen of an adult female insect, with 

 position of dorso-pleural line as indicated {a-a), and in which the limb bases 

 form the coxae and subcoxae {Sex) of thorax, but unite with the sterna of 

 abdomen, except in the genital segments {VIII, IX) and the eleventh segment 

 {XI). 



where the latter are distinct (fig. 2 C, D, E, F), but where appendages 

 are absent it must be assumed to follow the line of fusion between the 

 limb bases and the primitive sterna (fig. i C). 



Surface regions of the abdomen. — The dorso-pleural line is fre- 

 quently marked on the abdomen by a distinct longitudinal fold or 

 groove of the integument running ventrad of the spiracles (fig. 14 A, 

 a-a), the dorso-pleural nature of which is shown by the fact that 

 the area above it corresponds with the dorsum of the thorax contain- 

 ing the tergal plates and the paratergal wing bases, while the area 



