112 Wisconsin Academy of Sciences, Arts, and Letters. 
branches of the inner fork of B, but from the inner side, a small 
branch passes off to the sub-oesophageal ganglion. 
The dorsal branches are shown on the right in the figure (Fig. 
1.) while those ventral to the intestine or which pass to external 
respiratory filaments are shown on the left. A regular series of 
large branches is seen _to supply the intestine with the excep¬ 
tion of the oesophagus proper. Each of these branches breaks 
up in a complex fashion on its own side of the intestine. The 
large intestine is particularly well supplied with numerous small 
branches v r hich are not arranged on the regular plan of the 
mid-intestinal supply. A smaller longitudinal trachea lying on 
either side of the dorsal median line is formed by the union 
of loops arising from the main trunk. Additional similar loops 
in the meso- and metathorax are peculiar for the manner in 
wdiich they dip down toward the leg joints, there giving off in 
each case a branch which, aided by two others, supplies the two 
pairs of limbs arising from these segments. There is a sug¬ 
gestion here that these loops may later become the source of sup¬ 
ply for the wings also. Of the three branches supplying the 
meso-and metathoracic legs, the one sweeping in a curve toward 
the median line before entering breaks up in the first segment 
of the leg. The second fork of this same branch passes to the 
second segment, while that from the loop continues to the ex¬ 
tremity, supplying the remaining segments. The branches sup¬ 
plying the thoracic ganglia all unite with their opposites by a 
small anastomosing branch just anterior to the ganglia. The 
spinning glands, notwithstanding their activity in the secretion 
of silk, receive no regular supply of important tracheae, the 
only noticeable branch being a small one in the prothorax. The 
branches connected with respiratory filaments are marked with a 
circle at the point of exit through the body wall. Some of the 
external filaments consist of several branches, in which case 
the tracheae break up accordingly. 
Alimentary Tract.— The alimentary tract is straight, of 
the same length as the body, and begins at the mouth as a 
small thin-walled tube. It extends to about the end of the met¬ 
athorax with but little variation in size, narrowing slightly at 
the junction of the head and thorax, thence gradually widen- 
