42 MR. LUBBOCK ON THE DISTRIBUTION 



serve tlie ends of the tracliese ; but the larger branches were like those of the testis. In 

 Musca, Aphrophora, Tiimla, Forjicula, and Fanorpa there seemed to be no tracheae. In 

 MHstalis the testes are almost sessile ; and in Necropliorus mortuorum the vas deferens is 

 too short to give a good view of the tracheee. 



Ductus ejaculatorius. (PI. III. fig. 17.) 

 In Bomhii,s terrestris and in Fanorpa this organ has no tracheae. In Musca the 

 tracheee are in tufts, as in so many other parts of the body. In Necropliorus vespillo and 

 Eristalis they are like those on the testis. In Fentatoma, finally (PL III. fig. 17), the 

 oro-an 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 

 oro-an without dividing any more. They are generally straight ; but some were in coils, 

 which, however, may perhaps not be their natural position. 



Epidklijmis. (PI. III. fig. 20.) 

 PI. III. fig. 20 represents the mode of distribution on the epididymis oi Bomhus 2yratormn. 



VesiculcB seminales. 



In Bombus terrestris, B. muscorum, and B. derhamellus, the trachese are in tufts, the 

 tubules often being branched again two or three times : the tj^pe is much like that on the 

 heart ; but each tuft occupies much more space. On the heart I always found the tubviles 

 waved, which is not the case in those of the vesiculge seminales. 



In Necropliorus mortuorum and N. vespillo they may be seen very well. They are large, 

 and their manner of branching is more or less dichotomous. 



lu ApjJiropliora spumaria they are like those of the testis, and are therefore not very 

 diiferent from those of Necropliorus. 



In Fanorpa I did not see them well ; but they seemed to be like those of Necropliorus 

 and Apliropliora. 



In Musca and Eristalis the tracheEe are in tufts, as is the case throughout these insects. 

 In this organ the tufts are rather large. 



Female Oenerative Organs.— Ovaries. (PI. III. figs. 1 to 12.) 



In Bombus terrestris, B. muscormn, B. lapidarius, B. pratorum, B. hortorum, and 

 Vespa, the egg-tubes are covered by such an immense number of trachese, tliat 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 

 of Tenthredo. 



The large trachese give off short stout branchlets at smaU intervals. These branchlets 

 stop aljruptly, and give 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. 



