The Development of the Wings of a Caddis-fly Platyphylax designatus Walk. 595 



Tr, trachea; Mes, mesotliorax, also luesothoracic; 



Pp, peripodial pore; • rudiinent or wing; 



P.cav, peripodial cavity; Met, metathorax, also metathoracic 



Pro, prothorax; rudiment or wing. 



Plate XXVII. 



Fig. 1. Transverse section of a larva, just emerged, sliowing one of the 

 pockets on the side of the tliorax along the outer wall of wliich the wing rudiment 

 develops. The area of the wing rudiment is indicated by a bracket and it 

 will be noticed that here the cuticular layer is thicker and much darker than 

 over the rest of the pocket. Just inside the cuticula is the layer of hypodermal 

 cells. xllOO. 



Fig. 2. From a transverse section of a larva 5 mm in length, showing 

 the hypodermal layer which Covers the area of the wing rudiment of a larva. 

 Cuticular layer not shown. xllOO. 



Fig. 3. Section throügh the area of the wing rudiment of a larva 5 mm 

 long — a little later stage than figure 2. The cuticula is drawn and shows the 

 darkened portion under which the wing rudiment has started to develop. x 1100. 

 Fig. 4. Trans verse section through the thorax of a larva 7,5 mm long 

 showing that within the area of the wing rudiment the cuticula (cu), is without 

 setae and the hypodermis, Hyp., free from pigment. Dots in the cytoplasm re- 

 present the pigment granules. xllOO. 



Fig. 5. Section of the developing wing rudiment from a larva 8,5 mm in 

 length. The nuclei of the central cells in the wing rudiment are now arranged 

 radially to the surface. The part here figured is represented in the bracket in 

 figure 6. x 1100. 



Fig. 6. Entire pocket from a larva 8,5 mm long. The bracket shows the 

 part more highly magnified in figure 5. x 140. 



Fig. 7. Wing rudiment from a transverse section of a larva 6 mm long. 

 Beginning of invagination. Outer surface above. Cuticula not drawn. x 1100. 

 Fig. 8. Section of the wing rudiment from a larva 10 mm long showing 

 a further stage of invagination. Exterior to the invaginated part the cuticular 

 layer was thick and brown. The secretory activity of the cells is shown in the 

 Strands which are seen from the outer surface of the cells connecting, in part, 

 with the inner surface of the cuticula which, in the section, has been pulled 

 slightly away from the hypodermis and is omitted from the drawing. x 875. 

 Fig. 9. Surface view of wing rudiment from a larva 10 mm in length; 

 the disk has invaginated below the surface. x 280. 



Fig. 9-4. Section of the wing rudiment from the opposite side of body of 

 the same larva as figure 9. x 280. 



Fig. 10. Surface view of wing rudiment. Shown in section in the next 

 figure. X 280. 



Fig. 10 J. Section of the wing rudiment from opposite side of body to 



figure 10. Position of section represented by line a—a in preceding figure. x 280. 



Fig. 11. Surface view of wing rudiment from the mesothorax of a larva 



10 mm long. The peripodial pore is more apt to be rounded than is figured here. 



x280. 



