36 MR. LUBBOCK ON THE DISTRIBUTION 



Crop. (PL I. fig. 13.) 



The walls of the crop are generally strengthened hy a thick chitinous layer which pre- 

 vents the fine ends of the tracheae from being well seen. It is also generally surrounded 

 by muscular tissue. In AcJieta domestica it is provided with twelve longitudinal tracheas 

 in six pairs which are joined at the base, and send off transverse branchlets at regular 

 intervals. 



In Carahus there are about ten longitudinal tracheae which send out some large branches 

 at acute angles, and many cross-branchlets (PL I. fig. 13). At the posterior end the 

 great longitudinal tracheae are connected by a transverse vessel. 



In the larva of Lampyris the tracheae are as on the stomach. 



In Fanorpa they form a network, as in Carabus. 



Stomach. (PL II. figs. 1 to 10.) 



In Bomhiis terrestris, B. lapidar'ms, B. muscorum, and B. hortorum, the stomach is 

 divided into two parts : along the anterior run several large longitudinal tracheae which 

 anastomose freqxiently, while on the posterior portion the tracheae are mostly transverse. 

 In B. pratorum this anterior part is shorter than in B. terrestris. The tracheae give off 

 branchlets which generally end in tufts (PL II. fig. 5), but the tubules themselves branch 

 a good deal ; so that often the character is almost lost, as in the right-hand tuft in the 

 figure. PL II. fig. 11 represents some of the tracheae of the larva of B. muscorimi. 

 The branchlets are longer than is the case in the perfect insect, and the tubules are longer, 

 straighter, and fewer, — generally, indeed, only three in a tuft. In Vespa the tracheae 

 resembled those of Bomb us. Often, however, instead of ending in tufts, the branchlets 

 terminated as in PL II. fig. 10, the long tubules running up a muscle. Op)Jiion (PL II. 

 fig. 3) is characterized by very long branchlets (one-fortieth of an inch in length, 

 without a division), which at last break up more or less dichotomously into numerous 

 tubules. In Tentliredo, a genus belonging to the Ichneumonidae, the type was much like 

 that of Ophioii, but altogether much smaller. The same is the case with Cynips lignicola. 

 In Athalia spinarwn and Tenthredo, as in Borubus and Vespa, the tracheae anastomose 

 frequently on the front part of the organ. 



In Ichneumon the tubules are straight, or liut little waved, long, few, and more or less 

 at right angles with the branches from which they spring. 



In the Cricket the stomach is divided into two distinct parts. The walls of the first 

 {fot Leon Dufour's fig. 19*) seem to consist of large cells, round which the tracheae run. 

 They (PL II. fig. 9) are short and broad, and anastomose frequently. 



On the posterior part {h of Leon Dufour's figure) are numerous dark glandular bodies. 

 A great riblion-like trachea runs along the organ and gives off transverse branches. On 

 one side these branches much resemble trees (PL II. fig. 4), and the glandular bodies 

 look like some enormous kind of fruit. On the other side of the main trachea, the mode 

 of branching is similar, but the branches are more elongated. 



* " Recherches Anat. et Phys. sur les Ortliopthres, les Hymhiopteres, et haNevroptcres," ' Mem. d. Sav. Etiangers,' 

 vol. vii. 



