42 A, MANUAL OF .ZOOLOGY 



projection, the epiphysis or pineal gland.' (On the function 

 of this gland see Weidersheim and Parker, page 155). 

 Anterior to the base of this, tube remove a little of the 

 membrane and find the third ventricle. The posterior 

 part of the fore-brain is called the thalamencephalon. On 

 the ventral side of the brain back of the thalamencephalon 

 find the optic nerves. On the dorsal and the lateral side 

 of the brain back of the diencephalon or the mid-Brain 

 are the two optic lobes. Partly overlapping the optic 

 lobes and extending backward is the cerebellum which 

 constitutes the anterior part of the hind-brain. The taper- 

 ing part of the brain back of the cerebellum, is the medul- 

 la oblongata. The cavity in the dorsal part of this is 

 the fourth ventricle. Running forward from this demon- 

 strate the narrow passage, the iter or aqueduct of Sylvius. 

 From the third ventricle demonstrate the passages into 

 the lateral ventricles and into the olfactory lobes. The 

 side walls of the third ventricles are the optic thaiml. 

 On the ventral side of the brain posterior to the optic 

 nerves note the hollow outgrowth from the fioor of the 

 third ventricle. This is the infundibulum on the end of 

 which is situated the hypophysis or pituitary body. Note 

 the cranial nerves coming from the medulla. Make a 

 drawing of the dorsal and the ventral views of the brain. 

 Open the vertebral column carefully and expose the spinal 

 cord. Note how the nerves are given off. Demonstrate 

 the posteri(y and the anterior nerve roots. Dissect out a 

 vertebra. Notice particularly the character of the articu- 

 lating facets. Dissect; owt the pectoral arch and note the 

 character of the articulating facets between tEe arch and 

 the fins. 



TELEOSTOMI. 

 Teleost (perch). 



NOTE— In working out this animal keep constantly 

 in mind the corresponding parts in the dog-fish and com- 

 pare them point for point." 



EXTERNAL FEATURES— How does the general form 

 compare with that of the dog-fish? Is it bilaterally sym- 

 metrical? What are Its dimensions? (Length of fish is 

 measured from tip of snout to base of tail fin. Length 

 of head from tip of snout to the posterior edge of oper- 



