42 
MR. LUBBOCK ON THE DISTRIBUTION 
serve the ends of the tracheae ; but the larger branches were like those of the testis. In 
Musca, Aphrophora, Tipula, Forficula, and Panorpa there seemed to be no tracheae. In 
Eristalis the testes are almost sessile ; and in Necrophorus mortuorum the vas deferens is 
too short to give a good view of the tracheae. 
Ductus ejaculatorius. (PL III. fig. 17.) 
In Bombus terrestris and in Panorpa this organ has no tracheae. In Musca the 
tracheae are in tufts, as in so many other parts of the body. In Necrophorus vespillo and 
Eristalis they are like those on the testis. In Pentatoma, finally (PI. III. fig. 17), the 
organ is pear-shaped, the vas deferens being attached to the swollen end. A number 
of branches start from the periphery, and soon give off several branchlets at acute angles. 
These branchlets run towards the posterior end, and go for almost half the length of the 
organ without dividing any more. They are generally straight ; but some were in coils, 
which, however, may perhaps not be their natural position. 
Epididymis. (PI. III. fig. 20.) 
PI. III. fig. 20 represents the mode of distribution on the epididymis of Bombus pratorum. 
Vesicular seminales. 
In Bombus terrestris, B. muscorwm, and B. derhamellus, the trachea? are in tufts, the 
tubules often being branched again two or three times : the type is much like that on the 
heart ; but each tuft occupies much more space. On the heart I always found the tubules 
waved, which is not the case in those of the vesiculae seminales. 
In Necrophorus mortuorum and N vespillo they may be seen very well. They are large, 
and their manner of branching is more or less dichotomous. 
In Aphrophora spumaria they are like those of the testis, and are therefore not very 
different from those of Necrophorus. 
In Banorpa I did not see them well ; but they seemed to be like those of Necrophorus 
and Aphrophora. 
In Musca and Eristalis the tracheae are in tufts, as is the case throughout these insects. 
In this organ the tufts are rather large. 
Female Generative Organs.— Ovaries. (PI. III. figs. 1 to 12.) 
In Bombus terrestris, B. muscorum, B. lapidarius, B. pratorum, B. hortorum, and 
Vespa, the egg-tubes are covered by such an immense number of trachea?, that at first 
sight they look almost like organs of respiration. The mode of distribution also is very 
different from that found in any other part of the body. In another specimen of Vespa, 
belonging perhaps to another species, the tubules were fewer, so as more to resemble those 
oi Tenthredo. 
The large trachea, give off short stout branchlets at small intervals. These branehlets 
stop abruptly, and grve off from their end a great number of fine tubules. These latter 
are so excessively numerous and so much twisted and interwoven together, that I was 
unable to trace any one to its end, or to determine whether they are branched or not . 
