178 



THE SPINY DOGFISH -THE SKATE 



(with the inferior lobes and the saccus vaseulosus). The pituitary 

 body (hypophysis) is attached to the under-surface of the infundibulum, 



(d) The optic lobes overlie the posterior part of the thalamencephalon, and 



represent the thick bulged-out roof of the mid-brain, the side-walls 

 of which are the crura cerebri and its cavity is the iter. 



(e) The large ovoid cerebellum partly covers the optic lobes in front and the 



medulla behind. It represents the thickened front part of the roof 

 of the hind-brain. 

 (/) The medulla oblongata, partly covered by the cerebellum, forms the 

 posterior part of the brain. It is produced forwards along each side 

 (restiform bodies), and is continuous behind with the spinal cord. Its 

 cavity is the fourth ventricle. 



Note that (a), (b) and (c) represent the cerebrum or fore-brain, (d) represents 

 the mesencephalon or mid-brain, and (e) and (/) represent the rhombencephalon 

 or metencephalon or hind-brain. 



Superior ophthalmic 

 V & VII-, 



Inferior ophthalmic Vy 

 Inferior oblique--^ 

 Superior oblique- 

 Anterior rectus 

 Pathetic IV- 

 Superior rectus 



Inferior rectus 

 Corpora restiformiaj 



Posterior rectus- -/ 



Spiracle - 



Semi-circular canal 

 of Ear- 



Olfactory capsule 

 •Olfactory lobe 



Cerebral lobe 



..Buccal VII 

 Thalamencephalon 



Optic II 

 ■Optic lobe 

 Maxillary V 

 Cere.bellum 

 Superior ophthalmic 

 V & VII 

 -Mandibular V 

 -Palatine VII 

 -Spiracle 

 -Mandibular VII 

 Hyomandibular VII 

 Hyoidean VII 



lossopharyngeal 

 IX 



;<;uis 



Visceral X 



Fig. 61. — The Dogfish {Acanthias, syn. Sqiudm). Brain (dorsal view), Cranial Nerves, and 



Eye Muscles. 



