250 



six spinal nerves of the right side seen from 

 the lateral aspect. The two crosses indicate 

 the position of the foramen magniini. The 

 cranial region is to the rig-ht of these, the 

 vertebral to the left. The reconstruction is 

 from the same series of sections as figures 

 23-26, but is not drawn to the same scale. 

 The formal shading of the ganglia is omitted 

 in the case of the first spinal for the sake of 

 clearness. The roots of most of the spinal 

 nerves lie internal to the ganglia and there- 

 fore cannot be shown. Their places of 

 origin, however, are indicated bj the oval 

 dotted areas. 

 Fig. 28. Transverse section through the fore-brain to 

 illustrate the asymmetry of this part of the 

 brain. The dotted line indicates the mid- 

 vertical plane. Most of the brain therefore 

 here lies to the right. Xote the fibres col- 

 lecting at the base of each bulbus olfactorius. 

 These ultimately form the olfactory nerves. 

 Drawn with the camera, Zeiss aa. oc.4. 



Plate X. 



Fig. 29. Plaice split up the middle from below into two 

 halves and spread out to show both sides of 

 the sensory canal system, x f . The anterior 

 extremity of the dorsal fin is not shown. 

 The shading indicates the innervation of the 

 sensory canals. Supraorhiial canals, cross 

 hatched (R. ophthalmicus superficialis, vii.) ; 

 Infranrhital canals, dotted (R. buccalis, 

 vii.) ; HyomandihuJar canals, shaded (R. 

 mandibularis externus, vii.) ', Lateral canals. 



