72 
MAMMALIAN ANATOMY 
communicate in the midline through the foramen interventricu- 
lare with the third ventricle. 
2. Diencephalon. —Note the epiphysis (or pineal body) above, 
the hypophysis (or infundibulum) below, and the lateral thicken¬ 
ings, the optic thalami. The cavity is the third ventricle. 
3. Mesencephalon. —Trace the cavity, the aqueduct of the 
cerebrum, through this, and note that the optic lobes are dorso¬ 
lateral thickenings of the walls. 
4. Metencephalon. —Note its dorsal outpushing, the cere¬ 
bellum. 
5. Myelencephalon. —Note the wide fourth ventricle, and its 
thin roof. 
C. COMPARATIVE STUDY OF BRAINS OF OTHER 
VERTEBRATES. 
Examine other available demonstration dissections, such as 
the brain of some amphibian (Necturus or frog), and the brain of 
a reptile (turtle), a bird, and a primitive mammal (rodent), and 
identify the various brain vesicles and their more important 
features. 
Draw as many as time permits. 
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