238 



PSYCHE. 



[May 1S95. 



venation of the latter i.s similar to that 

 of Micropteryx, veins IVi IVo not 

 being connected b}' a cross vein with 

 III and its branches, and veins II and 

 III, with their branches, being sepa- 

 rate. The veins and their numbering 



consist of two layers, an ontei {U) and 

 inner (c), which takes a stain and lies 



are intlicatetl by Spuler's figure of 

 Talaeporia pseudobotnhyceUa (Fig. 4) 

 and one we have drawn of Hepiahis 

 tuustelinus (Fig. 5). 



/ 



Fig- 5' 



The structure of a complete vein is 

 described by Spuler. In a cross-section 

 of a Noctuid ( Triphaena pronuba 

 Fig. 6) the chitinous walls are seen to 



^ Fig. 6. 



next to the hypodermis {/ly). In the 

 cavity of the vein is the trachea (//-), 

 which shows more or less distinctly 

 the so-called spiral threatl ; within the 

 cavity are also Semper's rib (/■) and 

 blood corpuscles {be), which proves that 

 the blood circulates in the veins of the 

 completely formed wing, though this 

 does not appiy to all Lepidoptera with 

 hard matiu'e wings. I have 

 been able to observe the same 

 structure in sections of the 

 wing of Zygaena. 



A cross-section of a vein of 

 the immature pupa of Picris 

 brassicae shows that the 

 large trachea is first formed, 

 and that it extends along the 

 track between the protoplas- 

 mic threads connecting the 

 two hypodermal layers. 



The main tracheae throw 

 orton both sides a number of 

 secondary branches showing 

 at their end a cell with an 

 intracellular tracheal struct- 

 ure ; these accessory tracheae afterwards 

 branch out. 



The accessory or cross-tracheae often 

 disappear, though in some moths they 



