Optic lobes 



Cavity of optic lobes 



Supraorbital bar 



Commencement of Her 



Hypoaria 



Rectus sup. and inf. 



. Lens and retina 

 Outer trabecular unit 



Pituitary space of right twin head 



Palato-pterygoid bar 

 Inner trabecular units, fused 

 Visceral arch cartilage III 



I (Meckel's) 



'.', ,, ., II (hyoid) 

 Copular cartilage IV 

 17. -Tranav series (do"' 



with union at optic lobesi utrated in the t. 



figures. The section is further back than in Fig. 36. Evidences ol 

 duplicity are disappearing, but some are still to be made out, e.g. 

 two sets of infundibular downgrowths in the floor of the brain, and 

 two pairs of trabeculae, of which the inner, or adjacent, units have 

 united to form a mesial bar separating the two pituitary spaces. 

 Compare with PI. III. fig. 16 (normal) and with PI. XIV. fig. 50 

 (union at medulla). Other references under PI. I. fig. 4 and plane 

 of section in PI. XXI. figs. 88-00, line 37. ( X2O.) 



Periotic cartilage 

 (posterior end 



and 

 inni- > 

 line 38. ( 



Posterior end of composite medulla 



Lateral muscle segments 



Outer parachordal bar 



Inner parachordal bar 



- The two notochords 



The two aortae 

 Ganglion of vagus 

 Jugular vein 

 Pharynx 



The last visceral arch cartilage 



Sinus venosus 



Cartilage of pectoral girdle 



Auricle 

 Yolk 





J. F. 0. 



PL. 



