34 



British Dragonflics. 



certainly used as organs 

 of locomotion. Pressing 

 their legs against the 

 body, they sway the 

 abdomen from side to 

 side, and use the 

 lamellae somewhat as a 

 boatman does an oar 

 at the stern of a boat 

 in lieu of a rudder. In 

 this way the Agrionine 

 nymphs are able to 

 progress at a very 

 fair pace through the 

 water. That the}^ do 

 not breathe entirely by 

 means of the lamella; 

 is clear, for the}- often 

 lose them, and live 

 perfectly well without 

 them, but the\^ are not 

 able to move with so 

 much ease through the 

 water, even though they 

 sway their body to a 

 much greater extent.^ In the Calopterygiiuc, of the 

 three appendages, the central one only is lamellar, 

 but this sub-family seems to be possessed of an 



* Dewitz saw under the microscope "a stream of water pass in and 

 out of the end of the intestine " in an Agrionine nymph, and con- 

 sequently thinks that there may be a rectal means of respiration (Packard's 

 Text-Book of Entomology, p. 464, 484), but breathing is no doubt carried 

 on to some extent through the skin, especially in the younger nymjihs. 



Fig. 12.— Nymph of a Zygopterid 

 Dragonfly (Erythromjia naias). 



(Magnified). 



References same as for Fig. 11, except c.l. 

 Caudal Lamelte. 



