THE AUCHENORRHYNCHOUS HOMOPTERA. 215 



the root of the fore wings, either on the lateral margin of the 

 body (Cicada), or a little under the same {Aphrophora) . They 

 are hidden by the flattened-out, broad, prothoracic lateral mar- 

 gin, and can be seen very easily when this is cut away. They 

 are almost perpendicular {Cicada), or inclined postero-ventrally 

 (Aphrophora) ; they are always conspicuous, occasionally very 

 large (Tettigonia, Aphrophora) . 



2. Spiracles between meso- and meta-iliorax lie concealed under 

 the articulation of the hind wings, a little from the lateral mar- 

 gins on the ventral surface. They are smaller than {Aphrophora), 

 of equal size with {Cicada), or almost larger than {Fulgora), the 

 'first pair. In, for example, Fulgora they are externally visible 

 without preparation ; in the Stridulantia they are best viewed in 

 profile, as they are more or less covered by a posteriorly-directed 

 flap arising from the posterior margin of the mesothorax ; in the 

 Jassidse and Cercopidse they are covered by a similar plate- 

 shaped projection, and lie so completely hidden that they are 

 not easy to discover. 



b. Abdomen and its Spiracles. 



1. Strididantia. — The tergite of the first segment of the 

 abdomen is well developed, especially about the middle, but 

 much shorter than the following segments ; the sternite is also 

 well chitinized, especially in the male more strongly and pecu- 

 liarly. The second segment is solid throughout, without any 

 trace of membrane between the tergite and the sternite ; dorsally 

 it is quite as long as the following segments. Each of the third 

 to seventh segments is formed out of a sternite, which is far from 

 reaching the lateral margin of the body, and of a tergite, which 

 is extended to that lateral margin ; between the lateral margins 

 of the tergite and the sternite there is found a somewhat broad 

 band, which, according to the explanation here adopted, is taken 

 to be the Pleuron. This consists of two parts, viz. — externally, 

 a conspicuous "chitinous" plate, which (except in Cystosoma, 

 and partly in individuals of other forms with somewhat swollen 

 abdomen) is separated from the tergite by a very narrow, thin, or 

 somewhat thin marginal membrane ; and, interiorly, by a (except 

 in Cystosoma) distinct, narrow, thin membrane between the plate 

 and the sternite.* The tergite of the eighth abdominal segment 

 is coalesced with the pleural chitinous plate, whilst the sternite 

 is entirely modified as a genital segment. (The following seg- 

 ments are not considered either in this or in the following 

 families ; it will only be stated that one finds in both sexes of 



* The location of the spiracles in the third segment in, for example, 

 Tettigonia viridis suggests the reckoning of the plate as part of the Pleuron, 

 not as a ventral part of the tergite ; the structure in Cercopidae and Jassidse 

 suggests the consideration of the skin between the plate and the tergite, not 

 as a suture, but as a part of the Pleuron. 



