116 Annals Entomological Society of America [Vol. XIII, 



SUMMARY. 



Reviewing these facts briefly it may be said that the adapta- 

 tion to the submergence of tidal flats at some stage of their 

 existence has been acquired by Homopterous insects of several 

 different families, the Cicadid^, CicadelHdas and Fulgoridae and, 

 for the latter, three principal subfamilies that are so widely 

 separated that we may assume entirely independent origin for 

 the habit. In all then, five groups in which the adaptation is 

 present in greater or less degree. Even in the different genera as 

 Megamelus, Megamelanus and Liburnia there is no reason to 

 assume a common origin since many species in each genus are 

 entirely terrestrial. 



Each of the species found in this habitat is closely associated 

 with some one species of plant which in turn must be considered 

 as having been derived from a more strictly mesophytic habitat 

 and the conclusion seems warranted that the insect has simply 

 followed its host plant in this adaptation to hydrophytic 

 habitat. 



The structural modifications in all the species studied are 

 practically negligible but there is evidently a considerable phys- 

 iological modification to accommodate the insect to long periods 

 of submergence under water. The structures fitting the insect 

 for close adherence to its plant host were already developed 

 before the aquatic condition was met and if changed at all 

 would only need intensification to provide against the move- 

 ment of water. No special adaptations for swimming or skim- 

 ming on the surface of the water are present although these 

 insects, like practically all others when accidentally thrown on 

 water, will float and may to some extent propel themselves 

 over the surface by active movements in jumping or running. 



The physiological adaptations which seem probable present 

 a special problem and one which is apparently of considerable 

 interest but we have not had opportunity to follow it up. It 

 may be noted, however, that insects in general, especially when 

 inactive, are able to survive on a minimum supply of air. 



