46 
MR. LUBBOCK ON THE DISTRIBUTION 
simply the best authorities, without wishing thereby to express any decided opinion of 
my own as to their functions or homologies. 
In Bombus we find two sorts of appendages to the reproductive organs. One is the 
poison-gland, and consists of two long secreting tubes falling into an oval reservoir. On 
the tubes the tracheae are in tufts, but are very unlike those on the Malpighian vessels, 
though the tubes themselves are very like them. On the reservoir the mode of branching 
simple and 
The tubules are straight, or at least gently curved 
Between the ovaries of Aphrophora spumaria lies a membranous bag with tracheae 
much like those of the ganglia in Acheta. In one specimen, however, they were waved. 
On the spermatheca of Bombus muscorum tracheae were few, and the mode of branching 
simple. 
In Sydrophilus piceus there are certain ramified glands with swollen ends. On these 
lands the tracheae resemble those of the stomach. 
- 
Heart. (PL I. figs. 15, 16 & 17.) 
In Bombus terrestris, muscorum (PL I. fig. 15.), lapidarius, pratorum, and hortorum, 
Vespa vulgaris, and Apis mellifica, the larger tracheae branch freely along the margins 
of this organ, and anastomose frequently with one another and with the neighbouring 
systems, besides sending branches which run into those of the opposite side. The branches 
also give out short branchlets, which do not divide nor diminish in size, but terminate 
suddenly and give off from their end several smaller branchlets, which, again, divide more 
than once, so as to end in very fine, more or less waved tubules. The branchlets into 
which a branch divides are often of very unequal size. 
This character is, however, not common to all the Hymenoptera ; for in Ophion luteum 
and in one of the Ichneumonidae, though they had in most parts been torn off, yet in one or 
two places where they remained they divided into more or less waved tubules, by simple 
successive branching. 
This is also the case in Limnephilus vitratus, where, however, the tubules were larger ; 
moreover they were much obscured by the surrounding fat. 
Eor the same reason it was difficult to see them weU in Aphrophora, where, however 
(PL I. fig. 17.), after dividing several times, and generally dichotomously, they appeared 
to end in a tuft of long and apparently simple tubules. 
In the specimens of Acheta and Gryllus mridisswius which I examined, I was unable 
to make out the arrangement of the tracheae ; and in Locusta I was scarcely more for- 
tunate, but they seemed to end in tufts, almost as in Aphrophora. 
In Bentatoma the distribution was almost the same as on the oviduct, but generally 
with fewer tubules. They were sometimes waved, sometimes nearly straight. 
In Necrophorus they branched simply and were straight, or rather with gentle curves. 
After adding acetic acid, many of them were thrown into waves. 
InlAicanus cervus they were in folds, long, and with few branches, but all the ends 
had disappeared, as was also the case in Carabus and in Noctua gamma. 
In Enstalis, Musca (PL I. fig. 16), and Tipula, the tracheae are in small tufts consisting 
of from three to six tubules. These latter give off smaller ones from their sides. 
