JOURNAL, OF ENTOMOLOGY AND ZOOLOGY 71 



Is continuous with the line of separation between the two sides. 

 Quite a little farther down, the central fibers which are continuous 

 from the optic lobes meet with more ventral fibers which have 

 gradually been making themselves evident, and it is possible to 

 determine two additional masses of nerve fibers. It is at about this 

 level or a little before that the two sides of the brain are fused for 

 a short distance. The more dorsal mass of fibers represents those 

 followed from the optic lobes, the middle fibrous mass is the core 

 of the antennular portions of the brain, the ventral masses represent 

 the centers of the antennal lobes. These masses are connected to 

 the lobe or lobes near them. The middle fibrous portion does not 

 remain distinct for long. Farther down there is but one central 

 fibrous portion which may be called the antennal center. The con- 

 nectives with the ventral chain of ganglia are without accompany- 

 ing cells for only a short distance. 



The ventral ganglia were found to be in about the same posi- 

 tions as earlier authors have described. There are eleven centers 

 for the thoracic region and six for the abdominal. These thoracic 

 centers are in a sense ganglia very closely connected. There are 

 few indications of distinct right and left halves. The nerve cells 

 in a way correspond to the position of appendages which are at- 

 tached to this region of the body, but the dorsal and ventral masses 

 of cells are not exactly over each other. The dorsal cell groups 

 are especially interesting. They are found in great masses which 

 overhang in two directions, toward the caudal end and towards the 

 middle line, forming "neural crest" cells which may project so far 

 from the general mass of the nervous system as to be shown as 

 separate clumps of cells in cross sections. 



The six abdominal ganglia are well separated from each other 

 and at places show something of a paired nature. The nerve cells 

 are not so numerous and do not project from the general surface. 

 The last ganglion has but a few cells, mostly ventral ones. I agree 

 with Packard, who says that the nervous system is not very com- 

 plex, although one could learn very little from the figures which 

 he shows to support this conclusion. Of course, there are the 

 rather complex optic lobes connected with the stalked eyes, but 

 these and other parts of the brain are not complicated by the deep 



