iviii INTRODUCTION. 



In addition to the description given of Plate B, 

 fig. 4, r re|)resents the posterior translucent tense 

 membrane, and .s' the part of the outer chitinous 

 support of the abdomen. 



I have also dissected specimens of Cicada sent to 

 me from the North of Portugal and from Brazil. The 

 results are quite in accordance with those obtained by 

 the recent observers above noted. 



The Circulatory System. 



As the bodies of insects are well supplied with 

 trachea) and a plexus of air-tubes, there is no necessity 

 for blood-vessels, properly so called, and therefore they 

 do not exist. Thus, instead of the blood being brought 

 to special organs like gills or lungs, the necessary 

 oxidation is affected simultaneously by air-tubes, and 

 throughout all parts of the body. 



The Circulation of alimentary fluid is mainly carried 

 out through the many-chambered dorsal vessel or 

 chain-like heart, which, receiving the chyme transuding 

 through the walls of the intestines, is propelled from 

 the lower end forwards to the head ; from whence it is 

 discharged, (as has been shown by Herold,) directly into 

 the cavity of the body, bathing all the organs, and 

 entering even into the joints of the antennae and the 

 legs. After aeration, this nourishing fluid returns to 

 the posterior end of the dorsal vessel, where, after 

 mixing with fresh lymph, it is restored into the same 

 circle of circulation, through a kind of peristaltic 

 movement of the heart (vide Plate C). 



The Alimentary System. 



As in all Hemiptera, nourishment in the Tettigidtc 

 is drawn through a proboscis, which, united just before 

 the insertion of the salivary ducts, s s, is joined to an 

 oesophagus of varying length. According toBurmeister, 



