ANATOMY OF THE WESTERN CRICKET. 
177 
phageal ganglia, there are three thoracic ganglia, the last one being sit- 
uated opposite the insertion of the third pair of legs. There are six ab- 
dominal ganglia, the sixth and last one being the largest; the first one 
is situated quite near the last thoracic. 
The sympathetic nerve (Fig. 5, sm) is composed of two branches, which 
arise from the under side of the oesophagus, and extend back to the end 
of the crop (ingluvies) next to the proventricle, where two minute ganglia 
are situated, one on each side. There are three small sympathetic 
ganglia under and near the brain, the anterior one being called the 
frontal ganglion (Fig. 5,fg). 
The breathing apparatus consists, in insects, of air-tubes, called tracheae 
which originate at the breathing pores (spiracles), and ramify through- 
out the interior of the body, and thus carry the air into every part of 
the body ; thus everywhere comiug in contact with the blood, which 
flows freely into all the interstices of the body, among the viscera and 
muscles, not being contained in arteries and veins. 
There are two kinds of tracheae in the Anabrus, those which are simple, 
and those which are dilated, but there are no air vesicles or sacs, such as 
exist in the locust and other flying insects ; so far as is known no larval 
or creeping, unwinged insects possess air-sacs, and we see that in an 
insect like the Anabrus, when the wings are but partially developed, but 
not used to fly with, they are not present. 
The tracheae of Anabrus purpurascens are small where they arise from 
the spiracles, but certain of the branches after leaving the small spiracu- 
lar opening are dilated. There are eight sets of dilated tracheae in the 
abdomen ; the anterior ones are imbedded in the muscles of the sides of 
the body. The fifth set of abdominal dilated tracheae supply the ovaries, 
there being about 40 branches distributed among the tubes, one for each 
of the ovarian tubes. The sixth set send branches to the stomach, 
which is provided with eight large dilated tracheae, four on a side, 
by which the organ is held loosely in place. No tracheae are apparently 
sent to the ingluvies or crop. The seventh set of abdominal tracheae 
distribute their branches to the intestine, a pair of these being large ? 
long, sinuous, dilated tracheae. The tracheae branching from the eighth 
(and last) pair of abdominal spiracles supply the rectum, and a pair of 
dilated tracheae are very large, forming a barrel or spindle-shaped sac, 
situated on each side of the rectum just within the anus. These two 
large sac-like tracheae might at first sight be mistaken for true air-sacs, 
but they have the same structure apparently under the microscope as 
the tracheae themselves, the spiral thread being well developed. 
On the lower side of the abdomen, under the digestive canal, may be 
found the two main longitudinal (stigmatal) tracheae corresponding to 
the two stigmatal tracheae of Caloptenus. 216 They lie one on each side 
of the nervous cord, and are supplied with horizontal branches from the 
spiracles, and the pair extend into the head. 
sl6 Compare the description and Figs. 16 and 17 s, p. 268, First Report of the TJ. S. Entomological Com- 
mission, 1878. 
12 L 
