OF THE TRACHE/E IN INSECTS. 41 



Campcea margaritaria, Hipfarchia Janira, H. TWionus, Pieris napi, and Noctua gumma^ 

 there are many round glands, each with niiinerous tracheae. 



In Eristalis and Ilusca the tracheae are as on the stomach, though in the latter the 

 systems are particularly large. In both, there are several tongue-shaped glands with 

 numerous tracheae. In Tlpula also are several similar glands. A large trachea enters 

 the base of each, and there divides into four or five branches, of which about three con- 

 tinue nearly parallel, and give off branchlets from time to time, whUe the others diverge 

 to supply the basal part of the gland. In Pentatoma the trachese resemble those of the 

 stomach = 



Ilale Generative Organs.— Testis. (PL III. figs. 13, 1-1, 16, 18 & 19.) 



In Bombus muscorum, B. terrestris, and B. jyratormn, the trachese generally divide 

 dichotomously, but sometimes into three. The end tubules are very long, — a character 

 which we often meet with in the testis. In Acheta, Locusta, and Gryllus, the air had 

 always been removed from the fine ends, which therefore had become invisible. The 

 branches were, however, long between the branchlets, and they tapered very little. In 

 the pupa of Acheta, the trachea?, so far as they could be seen, resembled those of the 

 imago. In Musca the testis is a brown, sausage-shaped body, and the tracheae end in small 

 tufts (PL III. fig. 18). In JEristalis the organ is formed on a similar type. The tufts, 

 however, though larger, are more open, and consist of fewer branchlets. In AjyhrojjJiora 

 the tracheae are almost like those of the ganglia. They end in long, gently curved tubules, 

 which arise successively, and without forming tufts. 



In the button-like testes of Melolontha long trachese run from the centre to the 

 circumference. They divide three or four times dichotomously, and are very long. 

 They, however, diverge but slightly, and are a good deal twisted on themselves. In 

 Amj^himalla solstitialis they are very similar. PL III. fig. 16 represents one of the 

 least-complicated systems. In Necrojihorus mortuorum and N. vespillo the trachese 

 branch simply, small tubules rise from branches of considerable size, and the end tubules 

 are straight and of great length. In Carabus the ends of the trachese had disappeared. 

 In Cerambyx moschatus they were much like those oi Aphrojyhora spumaria. InPanorpa 

 the trachese were almost as in Necropliorus. Most of the ends had disappeared ; and yet 

 the fine tubules seemed to be very long, because they remained for a considerable distance 

 without any great diminution of size. When one of the branchlets divided, the two tubules 

 were each almost as thick as the branchlet from which they sprang. This character gives 

 the trachea a peculiar appearance, which is very striking. In Pentatoma the testis is 

 covered by broad, longitudinal, saccular trachese, which give off thick branches at the ends 

 and sides. 



Vas Beferens. 



This origin is often without trachese. When they are present, they are often very like 

 those on the testis, as for instance in Bombus terrestris, B. muscorum, B.pratorimi, Pen- 

 tatoma prasina, &c. In Acheta and Locusta it was thin, delicate, and apparently a's ithout 

 tracheae. In Grytlus, on the contrary, it is large and of a yelloAV colour. I did not ob- 



VOL. XXIII. G 



