EXPLANATION OF PLATES 



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

 at the level of the stage unless otherwise mentioned. 



ABBREVIATIONS 



a.L, antennary lobe n.c, nerve cord 



b.m., basement membrane oe., esophagus 



f.g., frontal gland o.l., optic lobes 



f.n., fontanel nerve ov., ovary 



fr.gn., frontal ganglion p.r.m.b., posterior root of mushroom 



■m.b., mushroom body body 



md.m., mandibular muscle ts., testis. 



PLATE 1 



EXPLANATION OF FIGURES 



6 to 17 Drawn from whole mounts of the heads of nymphs of L. flavipes. The 

 stippled portion of the brains represents the nerve cell layer, the fibrous core 

 is blank. Oc. 6, obj. 16, table level, reduced one third. 



6 Reproductive type, newly hatched forms, 1.1 mm., nine antennary 

 segments. 



7 Worker-soldier type, newly hatched forms, 1.1 mm., nine antennary seg- 

 ments. 



8 Reproductive type, 1.2 mm., ten antennary segments, third segment entire. 



9 Worker-soldier type, 1.2 mm., ten antennary segments, third segment 

 entire. 



10 Reproductive type, 1.3 mm., ten antennary segments, third segment 

 grooved. 



11 Worker-soldier type, 1.4 mm., ten antennary segments, third segment 

 grooved. 



138 



