34 
MR. LUBBOCK ON THE DISTRIBUTION 
were hardly any. The few that I could see were almost straight and branched at in- 
tervals. In Vespa there was only here and there a little tuft. 
On the commissures of Chrysopa, Fanorpa, and Libellula, I found no tracheae, and on 
those of Aphrophora only one here and there. In Pentatoma juniperina and P. bac~ 
canvm, on the contrary, both the commissures and the nerves were well supplied with 
waved tracheae, whose mode of branching needs no special remark. 
On the nerves of Insects generally I found fewer tracheae than on the commissures, 
and in most species many even of the larger nerves were without any. Whether this 
difference in different nerves be constant in each species, I am unable to say. 
(Esophagus. (PI. I. figs. 8 & 14.) 
The oesophagus is generally very poorly, if at all, supplied with tracheae ; indeed even 
when they are present they are attached to the muscular bands with which the organ is 
provided, rather than to the organ itself. 
In Pentatoma, Panorpa, the larva of Lampyris, Noctua gamma, Limnephilus vitratus, 
Aphrophora spumaria, Ichneumon, Ophion luteum, Vespa communis, Tenthredo viridis, 
Gryllus viridissimus, Tipula, and the larva of Mamestra, it appeared to have no tracheae. 
In Musca there is a ring round the pharynx very richly supplied with tracheae. On 
the upper part of the oesophagus the tracheae are in tufts, with waved or straight tubules ; 
on the posterior half there are a few longitudinal tracheae ; starting from the front end 
and running backwards, they give off waved, transverse, branchlets at intervals, and 
belong to the oesophageal muscles rather than to the organ itself. 
In IAbellula the oesophagus is narrow in front and swollen behind. The anter 
narrow part has no tracheae ; the posterior portion is supplied as in Musca, only that 
the branches rise behind instead of in front. In Necrophorus vespillo the type is 
almost the same. In Cerambyx moschatus the tracheae had more numerous transverse 
branchlets, but only their bases were visible. In Lucanus cervus and Amphimalla solsti- 
tialis they were similar, but with fewer branchlets ; the ends were invisible. In Carabus 
the tracheae are as in Forficula and Musca. In the larva of Lucanus the tracheae re- 
sembled those of the rest of the intestinal canal, while the larva of Lampyris seemed to 
have none. In JBombus they are few, waved, and simply branched. In the Orthoptera 
generally, the oesophagus is much swollen behind. 
In Forficula the type is the same as in Musca, but the lateral branchlets are larger 
and more branched. In Acheta domestica it is accompanied by two enormous tracheae, 
which are wide at each end and narrow in the middle. They give off large transverse 
branches, which are irregularly branched, somewhat like a system of rivers ; and the ends 
are finely and beautifully waved. Locusta is also well provided with trachea?, but the ends 
had become invisible. In the larva of Acheta the mode of termination of the trachea?, so 
far as it was seen, resembled that of the imago. 
In Eristalis the tracheae are unlike those of Musca; most of them are in tufts (PI. I- 
fig. 8), but are straighter and more delicate than those on the stomach. Here and there 
the character of tufts is almost lost, and they branch simply. 
