Observations upon the Development of the Teleostean Brain. 499 



Reference Letters. 



a.g. Ganglionic area of medulla oblongata. 



ag[. Aqueduct of Sylvius. 



a.S. Semicircular vesicular area. 



C. a. Anterior commissure. 



C. aq. Commissural band over aqueduct of Sylvius. 



cb. Cerebellum. 



C. c. Posterior commissural band of cerebellum. 



C. cr. Cruciform commissure of medulla in region of optic nerves. 



c. d. Dividing commissure. 



ce. Cerebrum. 



c.f. Coagulable fluid. 



c. i. Ventral commissure of infundibulum. 



CO. Commissural band in ventral edge of velum. 

 C. ol. Commissure at base of olfactory lobes. 

 C. op. Optic commissure. 

 C.p. Posterior commissure. 

 C. S. Superior commissure. 



d. b. Dice-box shaped vesicular area. 



f. Velum infrapineale : fold of thalamencephalic roof. 



f.g. Fornix of Gottsche, or valvula. 



fi. Fibres. 



fs. Fissure. 



in. Lumen of infundibulum. 



I. i. Lobus inferior. 



I. ol. Olfactory lobe. 



I. p. Lobus posterior. 



m. b. Mid-brain. 



ol. Olfactory sac. 



pa. Pallium, or roof of cerebrum. 



pn. Pineal body. 



pt. Pituitary body. 



r. i.p. Recessus infrapinealis. 



r. V. 3. Recess of the third ventricle. 



S. Septum in anterior region of optic ventricle. 



t. c Thin cellular median part of roof of optic ventricle. 



t. cr. Tegmen cranii. 



t.f. Labium invaginatum, or fibrous tract over the third ventricle 



behind the pineal body. 

 1. 1. 0. Tectum lobi optici. 

 t. 0. Optic thalamus. 

 t. S. Torus semicircularis. 

 t. th. Roof of thalamencephalon. 

 t. V. 4. Roof of fourth ventricle. 

 V. 0. Optic ventricle. 

 V. 3. Third ventricle. 

 V. 4. Fourth ventricle. 



