NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO 21 



removed to facilitate infiltration, the fibers v^ere not traced beyond 

 the proximal articles. The fibers are probably motor since they are 

 noticeably thicker and more heavily stained than those of the adja- 

 cent bundles, and they seem to originate from the nucleus which also 

 gives origin to the fibers of Ng. Thus they probably innervate the 

 intrinsic antennary musculature. The remaining bundles of fibers in 

 N7 stain less intensely and are undoubtedly sensory to the antennae. 



Two nerves, N9 and Nu, innervate the extrinsic musculature of the 

 antennae (fig. 2). This musculature is divided into a ventral and 

 dorsal group which insert on the proximal articles of the antennae. 

 The muscles originate on the cephalic plate and the tentorium. The 

 ventral antennary muscles are innervated by Ng which emerges from 

 the ventrolateral surface of the brain medial to the large trachea 

 (fig. 2) and about 60 micra posterior to the anterior limit of the brain. 

 The nerve sends fibers anteriorly to terminate in finer branches in the 

 ventral antennary musculature. The nucleus of origin of Ng is adja- 

 cent to the group of neurons which are associated with the intrinsic 

 antennary motor nerve (pi. 2, fig. 2). 



In hipimcticeps, only one nerve, Nu innervates the dorsal muscula- 

 ture (fig. 2). It emerges from the lateral surface of the antennal 

 lobes. Nio, which is a branch of Nu in Strigamia hirsutipes (see 

 Fahlander, 1938, p. 89), was not observed. The fibers of Nn do not 

 continue into the antennae with fibers of Nr but are clothed in their 

 own neurilemma. 



3. Nerves of the trito cerebrum. — The tritocerebral lobes and the 

 stomatogastric bridge are continuous with the antennal lobes ante- 

 riorly and the circumesophageal connectives posteriorly in bipuncti- 

 ceps. The only vestige of an unpaired frontal ganglion is a mass of 

 fibers and a few cells ventrally situated. The slight bulge which this 

 structure makes on the ventral surface is likely to be overlooked in a 

 gross dissection, since it is only about 50 micra in extent (fig. 2, N13, 

 pi. 3, fig. 3, stg). The stomatogastric bridge is formed from the 

 frontal ganglion and the frontal connectives. The stomatogastric 

 bridge represents the first anterior fibrous interconnection between the 

 two sides of the brain. It occurs about 190 micra posterior to the an- 

 terior limit of the supraesophageal ganglion. 



Fibers which contribute to the formation of N20 originate in the 

 neuropile of the tritocerebrum. After this nerve emerges from the 

 ganglionic mass, it gives rise to a branch (Nie) (fig. 2). This branch 

 innervates a longitudinal group of muscles located on either side of 

 the clypeal midline. Another branch (Nig) arising caudal to the first 

 branch, proceeds laterally to terminate on each side of the anterior 



