OF THE TRACHEA IN INSECTS. 39 
In Bentatoma the tracheae are like those on the stomach. 
In Campcea margantaria, Bieris napi, and the larva of Eupexio 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 tracheae were Ion- slender, and with few 
branchlets, at obtuse angles 
In Musca and Eristalh they are in tufts, as is so generally the case with the trache 
of these insects; while in the larva of ILvsca they are quite simple. A rather lar 
trachea runs along each Malpighian vessel in Tipnlo, and gives off little systems of 
branchlets at intervals (PI. II. fig. 18). 
In the larva of Bombus mnscorum the tracheae of the white urinary tubes resembled 
those of the stomach, but the branches generally ended in only two tubules. 
Ilium. (PI. II. figs. 11, 12 & 17.) 
In Bombus terrestris, B. mwtcorum, B. lapidarius, and B. hoHornm the walls of the ilium 
are composed of quadrangular cells, and the smaller branchlets of the tracheae run round 
and between them, so that they divide the organ as it were into quadrangular spaces. 'Flu's 
arrangement, however, I could not see well without the assistance of acetic acid. In Vespa 
the arrangement of the tracheae is much like that on the stomach. The same is the case 
in Ophion also, though the very long branches were not so much developed, and the whol< 
arrangement is on a smaller scale. At the front part of the organ in Tenth redo the tracheae 
branch frequently, and finally end in tufts (PI. II. 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 Athalia spiiiarum the larger branches are like those of 
Tenthredo. The tufts have fewer tubules, and often the branchlets end without any 
tuft at all. 
In Ichneumon the tracheae resemble those of Ophion. In Acheta (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 Gri/llus also the branches are 
more elongated than on the stomach. In Forficula auricula via the branches run in a 
wavy course along the muscles, with short transverse branchlets. 
In Necrophorus vespillo the ilium is very long, and covered with saccular ba-s. It 
has four longitudinal tracheae, which send a branch to each sacculus. 
In the larvae of Lampyris and Lucan us the tracheae are much like those of the stomach 
(PI. II. fig. 6). . 
In Banorpa, on the contrary, they are very different, but I was unable to see them 
satisfactorily. In Chrysopa again they are similar, but the branchlets are fewer. lAmne- 
philus vitratus has on the ilium several large tracheae which throw out rather numerous 
tubules. These latter are rather long and slightly curved, but not waved. The number 
of them is larger than is generally found on this organ. 
* 
Campcea margaritaria seemed to have no tracheae on this organ, nor on the caecum ; 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 Musca the tracheae branch very simplv, and resemble 
o 
