INTERNAL ANATOMY OF INSECTS. 45 
there is an open spiracle without lips a , to which, as in 
that beautiful bug Scutellera Stockeri, 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ones, as Reduvius, &c. this spiracle is obsolete.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 ru/ipes, 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 
1 Plate XXIX. Fig. 14, 15. m". b Ibid. Fig. 15. a. 
c Ibid. Fig. 14, 15. b. d Ibid. Fig. 25. {■". 
