118 



N. E. McINDOO 



and it seems that the cones are a later formation than is the outer 

 layers of the integmnent. In this larva the cones are usually 

 colorless, and, when stained, take up very little of the coloring 

 matter. 



The thickness of the integument in which these pores are found 

 varies considerably; the chitin of the mandibles (fig. 5) is 11 

 times as thick as that of the tarsus (fig. 13), and consequently 

 an entire pore cavity is never seen in any one section of a man- 



Figs. 14 and 15. Sections through tips of antennse, showing internal anatomy 

 of compound olfactory organs, including plate {PI), cone (Con), groups of sense 

 cells (SC), hypodermis {Hyp), neurilemma {Neu), nerve branches {NB) presumably 

 metamorphosing cells {BIC), and single olfactory organ {For). Fig. 14 is from 

 a longitudinal section, X 500; and fig. 15 is from a cross section, semidiagram- 

 matic, X 190. 



