BY R. J. TILLYARD. 



59 



the end of an instar, and about to cast its skin. The connection 

 between the internal lamina and the cuticle, so clearly shown 

 in Ris' larva, is not to be made out in the majority of the larva? 

 which I have studied. In fact, it can only be seen in two larvie 

 which were sectioned (as His' larva was) just before undergoing 

 ecdysis. The normal state of the lamina is shown in Text-fig. 3 

 and in Plate iv., fig. 29. It remains thus for the greater part of 

 an instar, and only acquires connection with the cuticle just 



Text-fig. 3. 

 T..S., through cuticle, hj-poderniis, and an inteiual lamina (il) fioin the 

 lateral triquetral gill of Calopteryx sp. ( x 370). al, an alveolus; />(/, 

 pigment-granules adhering to the inner wall of cuticle at a point where 

 the hypodermis is pulled away. Rest of lettering as on p. IlH(. 



before ecdysis. At the same period, the innermost strata of the 

 lamina become definitely hardened, so as to appear quite chitin- 

 ous, and these would seem to be actually withdrawn from the 

 lamina at ecdysis, by means of their connection with the cuticle. 

 Normally, the structure of the lamina resembles most closely 

 the formation seen in the cytoplasm of the hypoderm-cells at 

 their points of connection with muscle-fibres, and may therefore 

 be considered as fihrillar. The fibrillar material of the lamina 

 stains with haematoxylin as deeply as the hypoderm-cytoplasm 



