132 Journal of Comparative Neurology. 



diencephalon of Coliimba livia, taken through the corpus gcniculatum 

 externum. .-1, tract passing from mesencephalon to prosencephalon; 

 C. C, corpus geniculatum externum; C. (i. T'., tract from corpus genicu- 

 latum externum to prosencephalon; O. C, commissura Sylvii. 



PLATE XV. 



Fii^^i!- J-H- Horizontal longitudinal sections of the diencephalon 

 and mesencephalon of Columba livia. u, crescent-shaped nidulus; 

 C. G., corpus geniculatum externum; C. P., corpus posterius; d, tract 

 from within the mesencephalon to the external optic tract; F. /., fasci- 

 culus internus; ^'-, tract from mesencephal to prosencephalon; 111, mesen- 

 cephalic tract of fourth nerve; P. T., peduncular tracts; N. /., nucleus 

 inferius; O. C, commissura Sylvii; O. 7'., external optic tract; T. B., 

 tractus Bummi. 



Figs. T-10. Horizontal longitudinal sections through the dien- 

 cephalon and mesencephalon of Hylocichla szuaiiisoiii. a, crescent- 

 shaped nidulus; b, tract from mesencephalon to the prosencephalon; 

 C. G., corpus geniculatum externum; C. JV. T., central nidulus of the 

 thalamus; /. C, inferior commissure; JV. P., nidulus posterius; P. JV., 

 peduncular nidulus; ///, third nerve root; 77/ ;/, nidulus of third nerve; 

 1 V, root of fourth nerve; /I' «, nidulus of fourth nerve. 



Fiff. 11. Longitudinal perpendicular section of the diencephalon 

 of a chicken, a, tract from corpus geniculatum externvun to prosen- 

 cephalon; C. G., corpus geniculatum externum. 



Fig-. 12. Longitudinal perpendicular sections of the caudad portion 

 of the brain of Siaiici sia/is. Ill, root of third nerve; / f ', root of fourth 

 nerve. 



PLATE XVL 



Fig. 1. Cells from the nidulus pjriformis oi Hylocichla szvainsoni. 



Fig. 2. Magnified portion of the tectum of the cephalad portion 

 of the optic lobe of Hylocichla swaiiisoiii . 



Fig. 3. Cells from the crescent-shaped nidulus of Hylocichla 

 swainsoni. 



Fig. 4. Longitudinal perpendicular section of a portion of the 

 caudad part of the brain of a chicken. 



Fig. .5. Cells from the corpus geniculatum externum of Hvlocichla 

 swainsoni. 



Fig. 6. Cells from the optic nidulus of Hylocichla swainsoni. 



Fig. 7. Cells from the nidulus lenticularis of Hylocichla s-i'ainsoni. 



Fig. 8. Cells from the nidulus inferius of Meleagris gallipavo. 



Fig. 9. Cells from the peduncular nidulus of Hylocichla szcai/isoiii. 



Fig. 10. Horizontal longitudinal section of part of the brain of 

 Columba livia, to show the tract passing from the \icinitj of the third 

 and fourth niduli to the prosencephalon. 



7*7^,'-. //. Cells from the nidulus lenticularis of Hylocichla s-iiain- 



