38 
MR. LUBBOCK ON THE DISTRIBUTION 
the Malpighian vessels fall ; and on this the tracheae resemble those of the anterior 
division of the stomach. I have already given my reasons for considering all these 
organs as being together homologous with the stomach of other insects, though the 
'eat differences in structure certainly indicate differences of function. 
On the front part of the stomach two or three fine tubules rise from the large tracheae 
ear the base of each system, and run with only one or two branches all along the main 
r> 
branch of the system. What makes these tubules particularly conspicuous is, that while 
they are nearly as delicate as the ordinary tubules, they are much longer, and as straight 
as the larger branches which they accompany. 
On the round sac to which the Malpighian vessels are attached the tracheae are much 
like those of the front part of the stomach. 
The recurrent intestine of Aphrophora spumaria is not very richly supplied. The 
tracheae (PL II fig. 16) branch more or less dichotomously, and are waved at the ends. 
Malpighian Vessels. (PL II. fig. 15 ; PL IV. fig. 11.) 
In Bombus terrestris the tracheae run along the Malpighian vessels, giving off short, 
broad branchlets at intervals. Each of these ends abruptly, and from the termination 
spring from five to ten tubules. These tubules branch generaUy two or three times at 
acute angles, and are about ^ inch long. What, however, gives a very peculiar appear- 
ance to these tracheae, is, that the tubules of each tuft, and the branches proceeding from 
them, though somewhat divergent, are more or less parallel to one another. 
In B. muscorum, B. lapidarius, B. hortorum, Vespa vulgaris, Anthophora acervorum 
(PL II. fig. 15), the tracheae are like those of B. terrestris. 
In Ophion luteum long tracheae run along the Malpighian vessels, and give off side- 
branches here and there, which form little systems. In Tenthredo they are as in Ophion, 
but in Athalia spinarum they seem to have hardly any tracheae. 
In Acheta (larva and imago), Gryllus, Locusta, and Forficnla, a very long trachea runs 
along each Malpighian vessel, from one end to the other, giving off minute branchlets at 
intervals. The ends of these branchlets were always filled with fluid ; and I was there- 
fore unable to determine their mode of termination. 
In Libellula (PL II. fig. 19) this character was carried to an extreme, and it was onlv 
here and there that a little branchlet could be seen proceeding from the main trachea. 
In Panorpa the Malpighian vessels were so opake that the arrangement of the trachea, 
could not be made out. In Chrysopa they seem to have no tracheae. In Aphrophora 
the tracheae were badly seen. They appeared to divide dichotomously into curved, but 
not waved branchlets. 
„ In Jt^T* ° f La ™Py ri * they were long, waved, and either branched dichotomously, or 
gave off little branchlets at intervals, very much, in fact, as on the .^^u UI1U , 
In Necrophorus vespillo and N. humator the branchlets were more numerous, so as to ». . . 
almost the appearance of being in tufts. They are less wavy than in Lampyris. In Carpus 
tZZi X JZ t X Am ^ aaUa solstitialis , Melolontka vulgaris, and Lucunu* cmm 
z;:t is^ssr en examined were meAwith fluid - nd *-*» — * 
stomach and 
