46 MR. LUBBOCK ON THE DISTRIBUTION 



simply the best authorities, without wishing thereby to express any decided opinion of 

 my own as to their fvmctions or liomologies. 



In Bombtis 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 trachea3 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 

 is simple and successive. The tubules are straight, or at least gently curved. 



Between the ovaries of Aphroj)hora spimiaria lies a membranous bag with tracheae 

 much like those of the ganglia in Aclieta. In one specimen, however, they were waved. 



On the spermatheca of Bombus muscoriim tracheae were few, and the mode of branching 

 simple. 



In Hydropliilus jncetts there are certain ramified glands with swollen ends. On these 

 glands the tracheae resemble those of the stomach. 



Heart. (PL I. figs. 15, 16 & 17.) 



In Bombus terrestris, muscormn (PI. I. fig. 15.), lapiclarius, pratoriim, and hortomm, 

 Vespa mdgaris, 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 Opliion luteuni 

 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 Imniiep)hilus vitratus, where, however, the tubules were larger ; 

 moreover they were much obscured by the surrounding fat. 



For the same reason it was difficult to see them well in Ap>hrophora, wbere, 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 Aclieta and Grylhis viriilissimzis which I examined, I was unable 

 to make out the arrangement of the tracheee ; and in Locnsta I was scarcely more for- 

 tunate, but they seemed to end in tufts, almost as in Aphrophora. 



In Pentatoma 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. 



In Lucanus cerviis 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 Eristalis, Miisca (PL I, fig. 16), and T'qmla, the tracheae are in small tufts consisting 

 of from three to six tubules. These latter s^ive off smaller ones from their sides. 



