40 
MR. LUBBOCK ON THE DISTRIBUTION 
those of the salivary glands. In Eristalis the tracheae resembled those of the stomach ; 
in Musca they were perhaps rather more like those of the colon. The arrangement in 
Tipula is quite different, not being in tufts. In Aphrophora (PL II. fig. 16) they are 
much like those of the recurrent intestine and the Malpighian vessels. 
In the larva of Bombus muscorum the tracheae resemble those of the stomach. The 
different systems cross one another a good deal. The tracheae are stiff and wand-like, and 
end in small tufts of from two to four, long, straight, or gently curved tubules. These 
latter sometimes, though not often, branch dichotomously. In the larva of Lampyris the 
tracheae on the duodenum were like those on the ilium. 
Colon. (PI. IV. figs. 1 to 7.) 
In Bombus terrestris, B. muscorum, and B. lapidarius, the colon (PI. IV. fig. 2) was 
but poorly supplied, and the tracheae were long, with only a few branchlets. 
In Vespa the wall of the colon is divided into six parts, which have a cellular appear- 
ance, and are united to one another by their membranes. These membranes have no 
tracheae, but a large branch runs along each of the divisions, and gives off numerous side 
branchlets, a part of one of which is represented in PI. IV. fig. 5. 
In Ophion luteum the rectum contains a good many round glands ? which, as usual, are 
well supplied with tracheae. The mode of branching is much like that in Chrysopa 
(PI. IV. fig. 4). In Tenthredo and Athalia spinarum the colon contains six ellip- 
tical shield-like glands, which, as usual, are more richly supplied than the rest of the 
organ. The mode of branching is much like that of Ophion and Chrysopa. In Ichneumon 
also the rectal glands and their tracheae are as in Tenthredo. In Acheta the walls of the 
organ are divided into six compartments, each of which has a double series of tracheae, two 
large branches distributing themselves from near the middle, one to the front part, the 
other behind. The figure (PI. IV. fig. 6) which represents the front part of one division 
will give a more correct idea than any description could do. The colon of Locusta much 
resembles that of Acheta. The type is very nearly the same in Gryllus; but the lateral 
branchlets are fewer and longer. On the colon of the larva of Acheta the tracheae resemble 
those of the imai?o. 
In Forficula auricularia the colon contains six round shield-like glands in two alternate 
rows. In Carabus it is well supplied, and the larger branches anastomose a good deal. 
The muscles make it somewhat difficult to follow the ramifications of the finer branches ; 
but they seemed to be like those on the egg-tubes. In Cerambyx the tracheae seemed to 
resemble those on the stomach, as was also the case with the larvae of Lampyris and 
Lncanus. In Necrophorus vespillo and N. humator they are almost as in Bombus; but 
the branchlets are longer. In Libellula there are six wide longitudinal bands, connected 
by a membrane without any tracheae ; each band has a large trachea, which gives off about 
six systems of branchlets. Banorpa has also six rectal glands, each with a system of 
tracheae radiating from the centre. In Zimnephilus vitratus there were at least twenty- 
five round glands, on which the distribution of the tracheae was not unlike that of Chr r 
sopa Chrysopa has six round glands, as in Tenthredo, &c. The mode of tracheal dis- 
tribution in the glands and surrounding membrane is represented in PI. IV fi*. 4. In 
