NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO 29 



ning about 90 micra anterior to the caudal end of the brain this trans- 

 verse filet extends almost to the posterior boundary of the ganglion. 

 Heavily stained fibers interconnect the frontal lobes, the deutocerebral 

 lobes, and the bases of the tritocerebral lobes. Connections are also 

 made between the circumesophageal connectives at their anterior 

 end (pi, 4, fig. 2). This large commissure is obviously the most im- 

 portant association area in the brain of bipuncticeps. Although con- 

 nections with fibers derived from the three neuromeres are made at 

 every level, there is a pattern which can be resolved by resorting to the 

 postulated shifting of commissures (fig. 5). 



The majority of fibers which cross the large commissure in the an- 

 terior portion are derived from the lateral portion of the frontal lobes 

 (pi. 4, fig. i). This morphological observation identifies the anterior 

 portion of the tract as the "large protocerebral commissure" of other 

 authors. Fibers which are clearly derived from the deutocerebral 

 region are seen farther caudally. These fibers arch dorsally above the 

 cerebral vessel. Fibers from the dorsal bases of the tritocerebral lobes, 

 where the circumesophageal connectives take origin, are located still 

 more caudally. Arcuate fibers intercommunicate the tracts in the 

 connectives. This has been named the "commissure of the circum- 

 esophageal connectives" (pi. 4, fig. 2, COES). 



The position of the "commissure of the circumesophageal con- 

 nectives" is the only radical displacement of commissural elements 

 in the brain of bipuncticeps. The translocation of this commissure — 

 from a position (in the scutigeromorph brain) anterior and ventral to 

 the "large protocerebral commissure" (fig. 5) to one posterior to it 

 — is difficult to reconcile. The difficulty, however, is only spatial. 

 The fiber interconnections which are observed in the neuropile warrant 

 the homology. 



V. DISCUSSION 



THE GANGLIA 



The geophilomorph has a simply organized cephalic nervous system 

 and is the least complex of the chilopod brains. The spadelike cephalic 

 capsule has resulted in a wide separation of the supraesophageal and 

 subesophageal ganglia with a lengthening of the circumesophageal 

 connectives. The connectives are longer than those found in the other 

 chilopod orders. In the scutigeromorphs and insects the two ganglia 

 are practically one, and the esophagus courses through what appears 

 to be a single neural mass ; the connectives are short, if present at all 

 as observable entities. In bipuncticeps, however, the connectives are 

 long, thin, and cordlike. Its cephalic nervous system superficially 



