PLATE 1 



EXPLANATION OF FIGURES 



8 and 9 are drawn from whole mounts of the heads. Figure 10 is a combina- 

 tion drawing of the outline of the head and the brain, the latter added from a 

 dissected and mounted brain. The stippling represents the nerve cell layer, 

 the fibrous matter is blank. Obj. 16, oc. 6, stage level, reduced one-third. 



8 The head and brain of a nymph with long wing pads. 



9 The head and brain of a true adult. 



10 The head and brain of a njonph with short wing pads. 



EXPLANATION OP PLATES » 



All figures are drawn with the Spencer camera lucida and with Spencer lenses 



ABBREVIATIONS 



a.cm.. anterior dorsal commissure 



a.l., antennary lobe 



a.r.m.h., anterior root of mushroom 



body 

 h.m., basement membrane 

 C.6., central body 

 c.h.r., central body root 

 c.e., compound eye 

 cu., cuticula 

 f.g., frontal gland 

 f.n., fontanel nerve 

 fr.gn., frontal ganglion 

 gl., glia cells 

 hyp., hypodermis 

 i.cu., inner cuticula 

 i.f., inner fiber mass 

 la.n., labral nerve 

 Ih.n., labial nerve 

 l.J.n., labrofrontal nerve 

 m.h., mushroom body 



m.b.s.. mushroom body stalk 



fiid.n., mandibular nerve 



m.f., middle fiber mass 



ms., mesenchym 



mx.n., maxillary nerve 



oc, ocellus 



oc.n., ocellar nerve 



o.cw., outer cuticula 



oe., oesophagus 



o.f., outer fiber mass 



O.I., optic lobe 



p.l., protocerebral lobe 



p.r.m.b., posterior root of mushroom 



body ' 



r.n., recurrent nerve 

 sb.g., subesophageal ganglion 

 tr.cm., tritocerebral commissure 

 tr.L, tritocerebral lobe 

 V.C., ventral connective 



594 



