314 



The Large Poplar Longhorn 



In the ventral view of the pupa (Fig. 13) the various parts of the 

 head and mouth are clearly discernible. Anteriorly lies the vertex (v) 

 and in the centre the frons (fr) ; on each side is the gena (g) or cheek region. 

 The mandibles (m) are attached to the frons; between them lies the 

 triangular labium (pi). Below the mandibles are the labial palps (Ip) in 

 the centre, and on each side, a maxillary palp (p). 



The ventral surface of all the abdominal segments with the exception 

 of the last two is smooth. The penultimate or ninth abdominal segment 



Fig. 13. Pupa of S. carcharias, ventral view (greatly magnified), as = anal or tenth seg- 

 ment; fr= frons; ms$ = mesosternum; mts = metasternum ; tt = third sternite; x = first 

 leg; y= second leg; other letters as in Fig. 11. 



(nt) bears on its lateral margins a patch of stiff bristles. The last or anal 

 segment is somewhat triangular in shape ; it is enclosed by the eighth (et) 

 and the ninth (nt). There is a strongly marked sexual difference between 

 the anal segment of the male pupa and that of the female (see Fig. 14). 

 In the male (Fig. 14 b) this segment shows the anal opening (an) with a 

 small membranous plate (c) trapezoidal in shape on its anterior margin ; 



