572 ^^ • L. TOWER, The origin and development of the wings of Coleoptera. 



Fig. 68. Orthosoma hrunneum. A compound gland from the 

 elytron. 300 : 1. 



Figs. 69 to 76 incl. Leptinotarsa decemlineata. Stages in the 

 development of a permanent wing trachea, 300 : 1. 



Fig. 73. Phymatodes? A white or transparent scale from the 

 elytron. 300 : 1. 



Fig. 77. Phymatodes? A dark scale from the elytron showing a 

 unicellular gland opening at its base. 300 : 1. 



Fig. 78. Leptinotarsa decemlineata. An early stage in the form- 

 ation of a chitinous column. 400 : 1. 



Fig. 79. Leptinotarsa decemlineata. A chitinous column of the 

 elytron when nearly completed 400 : 1. 



Fig. 80. Leptinotarsa decemlineata. A compound gland from the 

 elytron. 400 : 1 . 



