262 Annals Entomological Society of America [Vol. V, 
to a branch that extends cephalad and somewhat parallel with 
the lateral nerves. This branch soon forks, one branch extends 
laterad across the lateral nerve, the other branch cephalo- 
laterad and parallel with the lateral nerve. 
Ventral Nerves ——In the mesothoracic and metathoracic 
ganglia, the ventral nerves (v) arise from the lateral margin of 
each ganglion in a plane ventrad of the lateral nerves. The 
metathoracic, ventral nerves extend cephalo-laterad, while the 
ventral nerves of the mesothoracic ganglion project directly 
laterad. In both cases the ventral nerves innervate the ventral 
portion of the body. At the point of entrance of the ventral 
nerves, one finds the usual trachee that supply the ganglion 
with air. 
Ventral Sympathetic System (Fig. 16, T. 3g, Fig. 17, T. 2g.)— 
With the mesothoracic and metathoracic ganglia, the ventral 
sympathetic system consists of a median nerve and transverse 
nerves. 
Median and Transverse Nerves——The median nerves (m) 
arise from the commissure in the cephalic angle of the diamond- 
shaped areas and in both cases are of considerable length 
before the fork. The mesothoracic median nerve is longer than 
the metathoracic median nerve. In both cases the transverse 
nerves (¢. 2.), after arising from the caudal end of the median 
nerve, proceed in such a direction as to cross the commissure at 
the point near where the connective nerves arise. After cross- 
ing the commissure, they tend to take, as usual a course parallel 
to the lateral nerves. The web or plexus (fx) of nerves in 
these two ganglia is very distinct; this is especially true in the 
metathoracic ganglion. The plexus occurs principally in the 
triangular area between the commissures, the lateral nerves, 
the transverse, and the connective nerves. In Fig. 17 (7. 1g, 
T. 2g), one may note a dark line drawn from the median portion 
of the prothoracic ganglion caudad. The true connection and 
relation of this nerve-like thread was not determined. 
PROTHORACIC GANGLION (Fig. 17, J. 1g).—The prothoracic 
ganglion is very similar in form and in the arrangement of its 
nerves to the abdominal ganglia. As heretofore mentioned, 
the commissure, which projects caudad from the prothoracic 
ganglion, is simple and large. The ganglion cephalad of the 
prothoracic ganglion is the subcesophageal ganglion and is 
located only a very short distance from the prothoracic ganglion. 
