INTERNAL ANATOMY OF INSECTS. 45 



there is an open spiracle without lips a , to which, as in 

 that beautiful bug Scutellera Stoclceri, a channel some- 

 times leads. The space in which this spiracle is planted 

 in other genera of bugs (Pentatoma &c.) is covered with 

 a kind of membranous skin, often much corrugated b . In 

 the aquatic insects of this section, and many terrestrial 

 ones, as Reduvius, &c. this spiracle is obsolete. There 

 is another circumstance, possibly connected with their 

 respiration, relating to many of the bugs, which may be 

 mentioned here. If you examine Pentatoma rufipes, a 

 very common one, you will find between the scapula and 

 parapleura a long orifice or chink; this upon a closer 

 inspection, under a good magnifier, you will see com- 

 pletely filled with minute stiff hairs or bristles, which 

 fringe the posterior margin of the scapula c . In a Bra- 

 zilian species of Lygceus (sexmaculatus K. M.S.) with in- 

 crassated posterior thighs, these hairs are replaced by 

 lamellae which have the aspect of gills. A red, vertical, 

 convex spiracle, with its orifice towards the head, and 

 terminating posteriorly in a kind of conical sac, is situated 

 towards the hinder part of the pleura in the giant water- 

 scorpion (Belostoma grandis d ) ; this seems analogous to 

 one lately mentioned in the mole cricket. In the other 

 section of this Order it is not easy to decipher the parts 

 of the under side of the alitrunk. In Fulgora, Cicada, 

 and many others of its genera, there appears to be more 

 than one opening into the chest ; but whether they are of 

 a pneumatic nature or not, can only be ascertained by an 

 inspection of the living animal. There is a very visible 



3 PLATE XXIX. FIG. 14, 15. m". b Ibid. FIG. 15. a. 



c Ibid. FIG. 14, 15. b. d Ibid. FIG. 25. A". 



