Procephalic Lobes of E})eira Cinerea. 455 



peudeut optic rudiments which arise ou the margin of the cephalic 

 fold. 



This question will not be settled by the study of the Araneid brain 

 alone but by a very careful comparison of typical Arachnids on the 

 one hand, and of the Vertebrata on the other. The suggestions con- 

 eerning the origin of the Vertebrata, which arise from these con- 

 siderations, demand that the problem should receive the most careful 

 attention. 



Acknowledgments. 



I take this opportunity for acknowledging my indebtedness to my 

 friend and teacher, Dr. William Patten, at whose suggestion this 

 study was undertaken, and under whose guidance it has been accom- 

 plished. I also take pleasure in recognizing the kindness of the 

 trustees of the Carnegie Institute, who placed a room at the Bio- 

 logical Laboratory at Wood's Hole at my disposal for the summer 

 of 1905, at which place a considerable portion of the work presented 

 in this paper was done. 



State Normal School, 



Framinghani, Mass. 



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