306 The Large Poplar Longhorn 



Between the pleurostome (Fig. 4, ps) and the anterior angles of the 

 frons (/), the antennae (a) are placed. Each antenna is sunk in a hollow 

 and is five-jointed; alongside the small fourth joint of the antenna and 

 external to it is the fifth joint, the smallest of all. 



On each side of the frons (/), to the outside of the antenna (a) and 

 somewhat posterior to the latter, is situated an ocellus (o). The ocelli 

 have the appearance of minute knobs or nodules. 



In Fig. 6 the view of the epistomal region is much enlarged and the 

 various details will be more clearly understood by referring to it. 



Looking now at the parts of the head posterior to the frontal suture (fs, 

 Fig. 4), one can make out the epicranium (epi) divided into two by the 

 epicranial suture (et), and lying in a groove (asm), the latter forming the 

 attachment area of the superior retractor muscles of the head. 



Fig. 6. Region of epistome, S. carcharias larva (very highly magnified), a = antenna; 

 c=clypeus; eps = epistome ; /= frons; /s= frontal suture; Z = labrum; o = ocellus; 

 ps = pleurostome. 



From the apex or posterior angle of the frons (/) a curved marking 

 may be observed to run across the epicranium. This marking forms the 

 anterior boundary of the portion of the head sunk in the first thoracic 

 segment. 



Looking now at the head ventrally (Fig. 10, b) one can distinguish 

 anteriorly the maxillae. 



Examining these parts in detail (Fig. 7), on each side (the outermost 

 parts in this view) lies the 1st maxilla, composed of five portions; the 

 cardo (c) ; next the stipes (st) bearing a few chitinous bristles and with 

 its posterior portion strengthened by a band of thicker chitin; the 

 maxillary palpifer (mxp) which bears a three- jointed maxillary palp 

 (mp) to the outside and the lacinia (la) to the inside, the latter covered 

 with stiff bristles. 



In the centre of the field lie the fused 2nd maxillae or labium. This 

 region of the mouth parts is made up of the mentum (m) and, the labial 



