OF THE TRACHE.E IN INSECTS. 
i:; 
From analogy with other tufted tracheae, it is probable that the tubules are lou , and 
that they branch occasionally. The impression, however, left on my mind after examining 
them carefully, was rather the reverse; but, as above stated, they lie so thickly together, 
that I cannot speak positively. 
In Tenthredo the tracheae were also in tufts, like PL III. fig. 4, which represents those 
of Tiptda, consisting, however, only of from three to ten tubules. These latter branch 
several times. However, the tracheae are far less numerous than in Bombus, and have 
altogether a very different aspect. In Ophion lufeum (PI. III. fig. 7) the contrast is still 
more striking. The tracheae are few, inconspicuous, and have entirely lost the tufted 
character. They give off straight branehlets at acute angles; and the end tubules are 
long, slender, and straight. The branches do not keep each to a single (---tube, but 
pass freely from one to another. In Athalia spiuarum the tracheae generally resembled 
those of Tenthredo, but they were not in such well-marked tufts. In a small species 
belonging to the Ichneumonidiv, the tracheae resembled those of Ophion, but the branch- 
lets were waved and twisted instead of straight. 
In Acheta the tracheae are much like those of Ophion, but on a larger scale. In Gryllus 
I did not get a good view of the tracheae, and especially not of their terminations. They 
were more waved than in Acheta. In Locusta (PI. III. iig. G) they were quite different 
from those of Acheta, or, so far as I could see them, of Onjllns. The large branches give 
off short stout branehlets, almost as in Bombus, except that they are more waved The 
branehlets end abruptly, and give off tufts of tubules, like those of Tenthredo. The 
tubules, however, are smaller in proportion to the branehlets, so as to afford a stronger 
contrast. Moreover they are less frequently branched. In Forficula (PI. III. fig. 9) 
I did not see the fine ends. The tracheae were simply branched ; and the branehlets 
were long, much twisted, and of uniform diameter for considerable distances. In Carabus 
the tracheae branch dichotomously towards their ends. The systems are rather large. 
Often two or three fine tubules spring from the side of the branehlets. In Lucanus cervus 
and Amphhnalla solstitialis I was unable to see the fine tubules. In Hydrophilus piceus, 
Necrophorus vespillo, and N. humator, the tracheae were generally in tufts, almost as in 
Bombus, but the tubules far less numerous. In these insects the tubules certainly divide. 
In Clmjsopa (PL EH. fig. 3) the tracheae end in tufts. The tubules in each are few in 
number, straight, and divergent like a fan. They often give off one or two still smaller 
tubules. Except that they are in tufts, they much resemble those of Ophion. The 
tracheae mFanorpa, IAmnephilus, and I believe also in Libelhda, resemble those of Chry- 
sopa. In Campcea margaritaria they are in tufts, as in Tenthredo-, but the tufts are 
not above a quarter as large as in that insect. In Sipparchia I was only once able to 
see the tubules. They are represented in PL III. fig. 8. Pigs. 8' and 8" represent all 
that was visible after intervals of a quarter of an hour. In Fieri* brassica also I was 
unable to see the finer branehlets. In Tiptda the tracheae were like those in PL III. 
figs. 4 & 5. Unlike as are these two figures, the mode of branching is in reality very 
similar, and would be seen if the tracheae of fig. 4 were extended as they are on the 
larger egg-germs. In Eristalis tenax and a large species of Musca (PL III. fig. 
the° tracheae were intermediate in character between those of Necrophorus and Bombus 
g 2 
