IX] 



THE RESPIRATORY SYSTEM 



181 



(2) The Papillate Type (fig. 80, 2, 3). This occurs in most 

 of the Gomphinae. The edges of both main and cross-folds are 

 broken up into long slender papillae, along each of which a strong 

 axial trachea runs almost to the tip. A small number of capillaries 

 (about twenty) arise from this trachea, each forming a complete 

 loop within the papilla. The papilla is strengthened externally 

 by frequent short transverse chitinous rods. Purple or mauve 

 pigment is developed below the bases of the papillae. This is 

 clearly a specialization from type (1), and of greater efficiency, 

 since the water bathes each papilla on all sides. 



Fig. 79. Portions of the freshly opened gill-basket, to shew form of gills. A. Parts 

 of three holobranchs from Austrogomphus ochraceus Selys (undulate simplex). 

 B. The same from Austroaeschna multipunctata Martin (implicate), c. The 

 same from anterior portion of basket of Atschna brevistyla Ramb. (normal 

 foliate). D. The same from Anax papuensis Burm. (papillo-foliate). E. The 

 same from Synihemit macrostigma Setys (archi-lamellate). F. Anterior halves 

 of three holobranchs from Diplacodes haematodes Burm. (neo-lamellate). 

 Original. 



The Duplex System (figs. 78 B, c ; 79 B-F ; 80, 4~n). 



In this system, the main-folds may be present, but not func- 

 tioning as gills (Aeschninae), or entirely absent (Libellulidae). 

 The gills are formed entirely from the double series of cross-folds, 

 which become enlarged to form twelve series, or hemibranchs, of 

 separate obliquely -placed or transverse gills, arranged in six double 

 series, or holobranchs. As will be seen from fig. 78, each holobranch 



