Walter Ritchie 309 



and the postscutellum (ps) dorsally (described more fully below); the 

 pleural zone or lobe medially; the bypopleurum (hyp), eusternum (es), 

 and sternellum (sll) ventrally. 



Dorsal to the pleural zone on each segment a spiracle (sp) is situated. 

 On each of the pleural folds there is a swollen band (pb) bearing fine hairs. 



The eighth body segment, in side view, has a similar appearance to 

 the first seven, only no parascutal, hypopleural, eusternal, or sternellar 

 lobes are present. 



The ninth segment is similar to the eighth, only it lacks spiracles and 

 shows no postscutal area. 



The tenth abdominal segment is divided by three deep sutures into 

 three lobes — one dorsal and two latero-ventral — which surround the 

 anus. 



Fig, 9. Dorsal surface of first thoracic segment of larva, S. carcharias. Head also shown 

 here in natural position (both parts greatly magnified), a = antenna; c = clypeus; 

 e^ji = epicranium; /=frons; fs = frontal suture; Z = labrum; m = mandible; o = ocellus; 

 pg = pronotal groove; ^/»=pronotum. 



Between the segments are bands of intersegmental skin (is). This 

 allows free longitudinal expansion and contraction of the segments. This 

 skin is more marked between some of the segments of the body than 

 between others. 



Looking now at the larva dorsally, one can see clearly the large 

 pronotum (Fig. 10 a, p) lying immediately behind the head. In the 

 enlarged view of this region (Fig. 9) the pronotum (pn) is seen to bear 

 on each side a curved groove (pg), running anteriorly and then sharply 

 bending backwards for a short distance. Between these two grooves 

 there are numerous chitinous asperities, while running transversely along 

 the anterior margin of the pronotum is a row of chitinous bristles. The 

 dorsal area of the second thoracic segment — the mesonotum — shows a 

 transverse row of very short stiff bristles along its anterior margin, 



