134 Journal of Comparative Neurology. 



The dorso-cerebral fiber tracts. 



The connections with the optic lobes. 



The anterior optic tract. 



The postero-superior optic tract. 



The antero-supcrior optic tract. 



The antero-postcrior optic tract. 



The posterior optic tracts. 

 The dorso-cerebral commissures. 



Tlie superior dorso-cerebral coviniissure. 



The anterior commissure. 



The optic commissures. 



The inferior dorso-cerebral coiiimissures. 

 The antenno-cerebral tracts. 



The inner antenno-cerebral tract. 



The middli antenno-cerebral tract. 



The outer antenno-cerebral tract. 

 The dorso-ventral tract. 



The ocellar nerves. 



P'ibers from the brain to the ocellar ganglia. 



The commissural and ventro-cerebral region. 

 The cell groups. 



The cells of the dorso-cerebron. 

 The cells of the ventro-cerebron. 

 Conclusion. 



Bibliography. 



Introduction. 



Since Viallanes' ( 88) monograph on the brain of the grass- 

 hopper {Oedopoda and Calopteiiiis) and the smaller but as excel- 

 lent work of Cuccati on the organization of the brain of So- 

 momya appeared nothing has been added to our knowledge of 

 the structure of the hexapod brain. In fact no one seems to 

 have worked at the subject. Such being the case, my endeavor 

 by an application of one of the more recent histo-neurological 

 methods to bring this subject into line with what is now known 

 relative to the stucture of the central nervous system of several 

 other invertebrates and more especially of the vertebrates will 

 doubtless be appreciated. Here, as elsewhere, an application 

 of the chief of the two recent methods, namely that of Golgi, 

 brings to light facts before known only from inference, and also 

 often materially alters conceptions based wholly upon the older 



