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SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 85 



eleventh somite. In the caterpillar (fig. ii) the eleventh somite is 

 apparently represented in the terminal segment by the four postpedal 

 lobes surrounding the anus (C, D), which may be supposed to be the 

 epiproct (Eppt), the paraprocts (Papt), and a hypoproct (Hypt). 

 There is, however, no evidence of a dual composition of the terminal 

 segment of the caterpillar furnished by the musculature of this seg- 

 ment. Both the dorsal and the ventral internal longitudinal muscles 



Eppt 



Fig. 42. — Musculature of the terminal segment and pygopods of a noctuid 

 caterpillar. 



A, dorsal muscles and leg muscles seen from below in terminal segment cut 

 open along mid-ventral line and spread out. B, ventral musculature of same 

 segment, seen from above. C, posterior end of abdomen, showing origins of leg 

 muscles. D, basal rim of left leg (L) and group of small muscles (b) lying 

 beneath dorsal retractors of planta (ii'sd). 



An. anus ; b, group of small antero-lateral leg muscles ; de, external dorsal 

 muscles ; di, internal dorsal muscles ; Eppt, epiproct ; /, intersegmental fold 

 between ninth and tenth segments; Hypt, hvpoproct ; L, basal rim of leg; /. 

 lateral muscles ; Papt, paraproct ; rvsd, dorsal retractor of planta ; rvsv, ventral 

 retractor of planta ; tv, transverse ventral muscles ; vi, internal ventral muscles ; 

 Vs, planta. 



(fig. 42 A, B, di, vi) extend continuously from the anterior inter- 

 segmental fold (/) to the epiproct and the paraprocts. Two large 

 sets of internal dorsal fibers (A, de) arise in the notches between 

 the epiproct and paraprocts and are inserted on the dorsal plate of the 

 segment. The eleventh segment, therefore, if represented here at all, 

 is reduced to the circumanal lobes ; and the fibers of the longitudinal 

 muscles of the tenth and eleventh segments have become continuous. 



