OF THE TRACHEAE IN INSECTS. ' 39 



In Pentatoma the tracheae are like those on the stomach. 



In Camp(sa margaritaria, Pieris napi, and the larva of Eupexia lucipara, the ends 

 became invisible so soon after death, that I was never able satisfactorily to see the finer 

 branchlets. In the larva of Mamestra the trachea? were long, slender, and with few 

 branchlets, at obtnse angles. 



In Musca and Eristalis they are in tufts, as is so generally the case with the trachea; 

 of these insects ; while in the larva of Musca they are quite simple. A rather larger 

 trachea runs along each Maljoighian vessel in Tipvla, and gives off little systems of 

 branchlets at intervals (PI. II. fig. 18). 



In the larva of Bombiis mnscorttm the trachese of the white urinary tubes resembled 

 those of the stomach, but the branches generally ended in only two tubules. 



Ilimn. (PL II. figs. 11, 12 & 17.) 



In Bonibus terrestris, B. miiscorwn, B. lajridaruis, and B. Itortormii the walls of the ilium 

 are composed of quadrangular cells, and the smaller branchlets of the trachese run round 

 and between them, so that they divide the organ as it were into quadrangular spaces. This 

 arrangement, however, I could not see well without the assistance of acetic acid. In Vespa 

 the arrangement of the trachese is much like that on the stomach. The same is the ease 

 in Ophion also, though the very long branches were not so much developed, and the wliole 

 arrangement is on a smaller scale. At the front part of the organ in Tenthredo the traehete 

 branch frequently, and finally end in tufts (PI. IT. fig. 17). At the posterior end, the 

 tufts are less developed, or altogether absent. In parts of the organ the larger branches 

 anastomose frequently. In Atkalia spinarum the larger branches are like those of 

 Tenthredo. The tufts have fewer tubules, and often the branchlets end Avithout any 

 tuft at all. 



• In IcTinemnon the trachea? resemble those of Ophion. IwAcheta (imago and larva) the 

 mode of distribution is much like that on the posterior end of the stomach, but at the 

 lower end the tree-like branches are more elongated. In Gryllus also the branches are 

 more elongated than on the stomach. In Forjiciila cmricularia the branches run in a 

 wavy course along the muscles, with short transverse branchlets. 



In Necropliorus vespillo the ilium is very long, and covered with saccular bags. It 

 has four longitudinal trachea?, which send a branch to each sacculus. 



In the larvae of Lampyrls and Imcanus the trachese are much like those of the stomacli 

 (PI. II. fig. 6). 



In Panorpa, on the contrary, they are very different, but I was unable to see them 

 satisfactorily. In Clirysopa again they are similar, but the branchlets are fewer. lArnne- 

 pJiilus vitratus has on the ilium several large tracheae which throw out rather numerous 

 tubules. These latter are rather long and slightly curved, l)ut not waved. The number 

 of them is larger than is generally found on this organ. 



Campcea margaritaria seemed to have no trachege on this organ, nor on the caicum ; or 

 at least they were so loosely attached, as, in the specimen examined, to have become 

 separated from it. 



On the long ilium in the larva of 3£nsca the tracheae branch very simply, and resonble 



