NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO 3I 



trinsic and extrinsic antennal musculature. The motor antennal nerves 

 in hipuncticeps originate from a nuclear group ventrally situated in 

 the antennal lobes. Motor fibers were identified in N7 and traced to 

 the same nucleus of origin as the fibers of N9 and Nn, the nerves to 

 the extrinsic antennal musculature. Fahlander reported that Nio, a 

 branch of Nn, innervated the dorsal musculature in 5. hirsutipes 

 and that Nn continued into the antennae with the fibers of N7. In 

 hipuncticeps however, Nio is absent and Nn itself innervates the 

 dorsal extrinsic musculature of the antennae. Fahlander may have 

 mistaken the fibers of one of the intrinsic motor nerves for those of 



No "free tritocerebral commissure" is present in hipuncticeps. 

 Saint Remy (1887) was not able to demonstrate it in Necrophloeo- 

 phagus longicornis and said that its absence is well explained by the 

 concentration of the tritocerebral ganglion. Fahlander admitted that 

 he did not find a continuity between N20 of one side and that of the 

 opposite side but still did not "doubt that the Geophilomorpha concur 

 in this respect with the other chilopod orders." His effort to homol- 

 ogize the four orders of centipedes hindered him from conceding 

 that a free tritocerebral commissure, which he had demonstrated in 

 the other three orders, could be absent in the geophilomorphs. 



It is customary to consider a dorsal motor and a ventral sensory 

 root in a typical arthropod ganglion (Wigglesworth, 1953). This 

 arrangement is inverted, however, with reference to the antennal 

 motor nerves in hipuncticeps. Their nuclei of origin are ventral in 

 position. In the subesophageal ganglion efferent neurosecretory 

 neurons are also ventral in position. Most of the neurons, in fact, are 

 ventrally aggregated in this ganglion. Experimental studies of nerve 

 degeneration and chromatolysis, as performed by Vowles (1955), 

 would probably indicate that the ventral surface of the subesophageal 

 ganglion is a motor area. It is hoped that this may be investigated in 

 the future. 



The nerves which innervate the mouth parts of hipuncticeps emerge 

 from the subesophageal ganglion, and in general, agree with the ar- 

 rangement in Strigamia hirsutipes. The nerves to the mandible, first, 

 and second maxillae, in S. hirsutipes, are equidistant from one 

 another; in hipuncticeps the nerves to the mandible and first maxilla 

 are anteriorly located while the nerve to the second maxilla is con- 

 siderably more posterior in position. This is probably related to the 

 fact that the ganglion of S. hirsutipes is spherical while that of hi- 

 puncticeps is elongate. The entire cephalic capsule of hipuncticeps is, 

 in fact, longer than that oi S. hirsutipes. 



