The oi'igin and development of the wings of Coleoptera. 571 



Plate 18. 



To show later developBierit and finer structure of the wings. 



rigs. 37, 38 and 39. Leptinotarsa decemlineata. Three stages 

 in the development of a unicellular hypodermal gland. 400 : 1. 



Figs. 40, 41 and 42. Epilachna horealis. Three stage in the de- 

 velopment of the deciduous spines. Figs. 40 and 41, 640: 1; Fig. 42, 

 320 : ]. 



Fig. 43. Coccinella hipunctatn. Section of elytron showing de- 

 velopment of tracheoles. 300 : 1. 



I'ig. 44. Leptinotarsa decemlineata. Section of elytron showing 

 formation and entrance of tracheoles. 320 : 1. 



Fig. 45. Chrysobothris femorata. Section of an elytron showing 

 the formation of a mass of tracheoles. 320 : 1. 



Fig. 46. Osmoderma scabra. Section of hind wing showing the 

 tracheoles ready to enter the wing. 300 : 1. 



Fig. 47. Prionus laticoUis. A compound hypodermal gland from 

 the elytron. 400 : 1. 



Fig. 48. Hippodamia 13])unctata. Section showing the devel- 

 opment of tracheoles. 600 : 1. 



Fig. 49. Leptinotarsa decemlineata. Reconstruction of an early 

 stage in the formation of a chitinous column of the elytron. 100 : 1. 



Fig. 50. Chrysobothris femorata. Section of elytron showing de- 

 velopment of chitinous fibres in the hj'podermal cells. 400 : 1. 



Fig. 51. Chrysobothris femorata. Section of an elytron showing 

 contraction of chitinous fibres and decreased thickness of the elytron. 

 200 : 1. 



Fig. 52. Chrysobothris femorata. Section of hind wing showing 

 thickened costal edge. 185 : 1. 



Plate 19. 



Fig. 53. Chrysobothris femorata. Prepupa with larval covering 

 removed to show position of appendages as seen in ventral view. 13: 1. 



Fig. 54. Chrysobothris femorata. Prepupa about two days older 

 than Fig. 53, ventral aspect. 13 : 1. 



Fig. 55. Chrysobothris femorata. Same specimen as Fig. 54 seen 

 from the side. 13 : 1. 



Fig. 56. Epilachna borealis. Prepupa with larval covering re- 

 moved to show position of appendages. 13 : 1. 



Figs. 57, 58, 59, 60, 61 and 62. Chrysobothris femorata. Six 

 stages in the development of the cuticula and the cuticula colors. Zeiss 

 appochromatic obj. 2 mm, oc. 12. Drawn free hand. 



Plate 20. 



Figs. 64, 65, 66 and 67. Hippodamia ISpunctata. Four stages 

 in the development of the elytra. 120 : 1. 



