EXPLANATIONS OF THE PLATES. 



The following letters have the same signification on all the plates: 



c, clypeus ; c 1 , its folds. m, mandibles. 



e, epipharynx. mp, maxillary palpi. 



/, fulcrum. 



h, hypopharynx. 



i, infraoesophageal ganglion. 



I, labium; I', I", its folds. 



Ib, labellae. 



Ir, labrum. 



Ir-e, labrum-epipharynx. 



mx, maxillae. 



oe, oesophagus. 



p, pharynx. 



pm, pm 1 , pharyngeal muscles. 



s, supraoesophageal ganglion. 



tr, tracheal stem. 



x, basal support of maxillae. 



The number of diameters enlargement is indicated against each figure. 







Greek letters are used to indicate where sections are made in probosces, 

 and the corresponding sections are indicated by the same letters, often with 

 an accent ('). 



Shaded parts of sections are portions filled with connective tissue, 

 nerves, air-spaces, and other parts having no significance in connection with 

 points discussed in the dissertation. 



