56 



McCLURE. 



Figs, 'ja, 'jb, 'jc. Longitudinal horizontal sections through the primitive fore-brain 

 of Amblystoma punctatum, showing the origin of the olfactory nerve from the olfac- 

 tory neuromere (^Nm I.) and its final fusion with the nasal thickening of the epiblast. 

 These sections are two or three apart. Z. 4 A. 



Fig. 8a. Horizontal section of Anolis sagrcei, dorsal, and parallel to the axis of 

 the primary fore-brain, showing the neuromeres of the thalamencephalon (TVw /. 

 and Nm 11.). Also A'w //. , which has the appearance of a portion of a neuromere. 



Fig. 9. Horizontal section of a four-day Chick, dorsal, and parallel to the axis of 

 the primary fore-brain, showing the neuromeres of the thalamencephalon. Z. 2 A. 



Fig, 10. Horizontal section through the superior portion of the brain of Petro- 

 niyzon. 22 mm. larva. Taken from Dr. Scott's plates on " The Embryology of 

 Petromyzon." 



Fig. II. Horizontal section through the anterior portion of the head of a 

 Petromyzon embryo just before hatching. After Scott. This section does not show 

 the primitive fore-brain, as it lies at an angle to the mid-brain, due to cranial flexure. 

 The oculomotor and trochlear neuromeres (^Nm III. and Nm IV.) lie anterior to 

 the trigeminal neuromere {Nm V.), between it and the primitive fore-brain. 



