MORPHOGENESIS OF THE CHOROID PLEXUSES 529 



taenia fornicis in all vertebrates where it is present, but that in 

 Chelonia and the forms above, it oversteps the taenia fornicis 

 and invaginates the posterior area chorioidea laterahs telencephaU 

 in the medial hemisphere wall and that this latter portion comes 

 more and more to dominate its development as we ascend the 

 vertebrate scale. 



I wish here to express my gratitude to Dr. S. Walter Ranson 

 for his unvarying kindness and interest throughout the progress 

 of this work. 



