1912] Anatomy of Tomato-worm Larva 265 
the ganglion, fork, one branch extending ventrad and the other 
more or less dorsad. These particular tracheze arise from 
branches that lead into the head from the spiracle located in the 
prothorax. 
Subesophageal Commissures—The subcesophageal commis- 
sures (s. c.) are the branches that arise from the ventral side of 
the crura cerebri near the supracesophageal ganglion. These 
two branches encircle the pharynx. On the caudal part of this 
semicircle two small branches occur which extend dorsad and 
innervate the large muscle fibres of the pharynx. These semi- 
circular nerves have received the name of commissures, but a 
comparison with other ganglia shows that they are not the true 
commissures. The crura cerebri should be called the commis- 
sures. It is probable that the so-called subcesophageal com- 
missures are nothing more than connective nerves that have 
united to form a semicircle about the pharynx. The following 
nerves arise from the supracesophageal ganglion :— 
Optic Nerves —The small optic nerves (0. 1.) arise the most 
cephalad of any of the nerves from the supracesophageal ganglion 
and without branching extend to the groups of ocelli on each 
side of the head where they break up into small branches and 
supply each ocellus. 
Antennal Nerves —The antennal nerves (at. n.) are of about 
the same size as the optic nerves and arise from the ganglion 
caudad of and adjacent to the optic nerves, and extend cephalad 
and ventrad. Not far from the ganglion, they fork and form 
two branches, one of which innervates the area at the base of 
the antenna and the other the antenna itself. 
Clypeo-Labral Nerves—The pair of clypeo-labral nerves 
(cl. Ir. n.) are the most caudal pair of the nerves arising from 
this region of the supracesophageal ganglion. Each clypeo-. 
labral nerve gives rise to several cephalo-mesal extending nerves 
and one caudo-lateral branch. The latter branch, arises from 
the clypeo-labral nerve in a plane slightly ventrad of the frontal 
ganglion and terminates in an enlarged ganglion-like structure 
on the labral aspect of the pharynx. This ganglion-like struc- 
ture gives rise to several small nerves. The first cephalo-mesal 
branch from the clypeo-labral nerve is very short and arises in 
a plane slightly dorsad of the frontal ganglion. The succeeding 
or second cephalo-mesal nerve from the clypeo-labral nerve 
connects with the Y-shaped branch given off from the frontal 
