714 EXTERNAL ANATOMY OF INSECTS. 



nels, which precisely resemble closed spiracles. These 

 may be denominated false or blind spiracles. Again, if 

 you examine the pupa of any Scutellera or Pentatoma, 

 in which tribe the true spiracles are ventral, you will 

 discover, placed in a square on the two or three interme- 

 diate dorsal segments, four or six elevated points resem- 

 bling spiracles, but not perforated, connected often by 

 corrugations in the skin or crust a : in the larvae also of 

 some Reduvii the first minute dorsal segment, at each 

 lateral extremity, has a similar elevation with a central 

 umbilicus precisely resembling a spiracle, but still not 

 perforated : another instance of false spiracles in this sec- 

 tion of the Hemiptera, is furnished by Aradus laminatus 

 before mentioned, in the perfect insect ; between the 

 spiracle and the margin of each ventral segment is a 

 white round callus, with a dark point resembling a 

 perforation on its exterior side, and terminating inter- 

 nally in a channel covered by membrane leading to the 

 disk of the segment, so that the whole in shape resem- 

 bles a tobacco-pipe b . A number of similar callosities 

 with a central impression, but without any channel, va- 

 riously disposed, are also to be found in another bug, 

 Rhinuchus compresslpes K. c In the Homopterous sec- 

 tion of this Order, a series of impressed points, which 

 may be easily mistaken for spiracles, are to be discovered 

 on both sides of the abdomen, at the margin in Centrotus, 

 in which the real spiracles are quite concealed. 



In spiders, as we learn from Treviranus, the open ven- 

 tral spiracles of the scorpion are replaced by pseudo- 



n Plate XXIX. Fig. 22. is part of the back of the abdomen of the 

 pupa of a Pcntatoma. a the pseudo-spiracle, b the connecting corru- 

 gations. b Ibid. Fig. 24. a. c Ibid. Fig. 27. a. 



