34 MR. LUBBOCK ON THE DISTRIBUTION 



were hardly any. The few that I coukl see were almost straight and branched at in- 

 tervals. In Vespa there was only here and there a little tuft. 



On the commissures of Clirysopa, Panorpa, and lAbelUda, I found no tracheae, and on 

 those of Aphrophora only one here and there. In Tentatoma jtmiperina and P. bac- 

 carimi, on the contrary, both the commissures and the nerves were well supplied with 

 waved tracheae, Avhose mode of branching needs no special remark. 



On the nerves of Insects generally I found fewer trachese 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 trachese ; 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 Tentatoma, JPanorpa, the laiwa of Lampyris, Noctua gamma, Limnepldlus vitratus, 

 Aphrophora spumaria, Ichneumon, Opliion luteum, Vespa communis, Tenthredo viridis, 

 Gryllus niridissimus, Tipida, and the larva of Mamestra, it appeared to have no trachese. 



In Ilusca there is a ring round the pharynx very richly supplied with trachese. On 

 the upper part of the oesophagus the trachese are in tufts, with waved or straight tubules ; 

 on the posterior half there are a few longitudinal trachese ; 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 Libellula the oesophagus is narrow in front and swollen behind. The ajiterior 

 narrow part has no trachese ; the posterior portion is supplied as in Musca, only that 

 the branches rise behind instead of in front. Iia Necrophorus vespillo the type is 

 almost the same. In Cerambyx moschatus the trachese had more numerous transverse 

 branchlets, but only their bases were visible. In Luca.mis cervus ajid Amphimalla solsti- 

 tialis they were similar, bu.t with fewer branchlets ; the ends were invisible. In Carabus 

 the trachese are as in Forficula and Ilusca. In the larva of Lucanns the trachese re- 

 sembled those of the rest of the intestinal canal, while the larva of Lampyris seemed to 

 have none. In Bombus 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 In'anchlets are larger 

 and more branched. In Acheta domestica it is accompanied by two enormous trache88, 

 which are vi'ide at each end and narrow in the middle. They give off large transverse 

 branches, v.^hich are irregularly branched, somewhat like a system of rivers ; and the ends 

 are finely and beautifully waved. Locusta is also well provided mth trachese, but the ends 

 had become invisible. In the larva of Acheta the mode of termination of the tracheae, so 

 far as it was seen, resembled that of the imago. 



In Eristalis the trachese are unlike those of Ilusca ; 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 b i'anch simply. 



