562 EXTERNAL ANATOMY OF INSECTS. 



there are two, as in Perga, being the stoutest, and con- 

 necting with the Costal Area, and the lower one with the 

 Anal. 



5. Pnystega a . We learn from M. Chabrier, that in 

 the common dragon-fly, a space, consisting of three 

 triangles, which immediately succeeds the frcenum, af- 

 fords attachment to no muscles, but merely covers aerial 

 vesicles 5 . This is the part I have called the pnystega c . 

 An analogous piece may be discovered in Phasma and 

 Mantis in a similar situation; but I cannot trace it in 

 Locust a Leach, or in the other Orders. 



Having considered the parts that constitute the meso- 

 ihoraX) we will next say something upon those, as far as 

 they require notice, that compose the medipectus or mid- 

 breast. But first I must observe in general of the me- 

 dipectus and postpectus taken together, or the whole un- 

 derside of the alitnm/c, that though usually they are in 

 the same level with the antepectus or under side of the 

 manitrunk, yet in several instances, as the Scarabceidce 

 MacLeay, the Staphylinidcc, &c. they are much more 

 elevated than that part; they are also usually longer, 

 very remarkably so in Atractocerus, but in Plater sul- 

 catus and many others they are shorter. These parts 

 are also commonly rather more elevated than the abdo- 

 men, — much so in some, as Molorchus; but scarcely at all 

 in others, as Buprestis, the Heteropterous Hemiptera, &c. 

 In some of the latter {Tetyra J\) the abdomen seems 

 the most prominent. Another observation relating- to 



o 



11 Plate IX. Fig. 7. m . 



b Chabrier Sur le Vol des Ins. c. iii. 354. 



c From Trviu to breathe and Hya to cover. 



