Cbap. VIII.] AT^D OF AMPHIBIA. 119 



But in such Fishes as the Whiting (fig. 65), the Carp 

 (fig. 52), the Skute (fig. 53), the Shark (fig. 48), and 

 others, the olfactory gangh'a are situated at a distance from 

 the cerebral lobes, with which they are connected only by 

 means of two long and narrow outgrowths or peduncles. 

 In these latter Fish the ganglia are to be found close to 

 the olfactory organs, from which they receive numerous 

 short nerves. 



Such are the essential parts in the brain of the Fish. 

 Their relative size or development is, however, subject to 

 almost countless diversities in different genera. 



From the foregoing description, it will be seen that 

 on3 of the principal characteristics of the Brain of Fishes 

 is to be found in the serial arrangement of its parts, in a 

 line with one another and with the spinal cord ; whilst 

 another is the small mass of the Brain as compared with 

 that of the Spinal Cord, and still more in comparison 

 with the mass and weight of the entire body. 



In the former respect, at least, the Brain of Amphibia 

 (fig. 56) agrees closely with that of Fishes. The principal 



Fig. 56. — Brain and Spinal Cord of the Frog a, Olfactory lobe.s ; b, cerebral lobes; 

 B, pineal body ; c and d, optic lobes ; e, cerebellum ; h, spinal cord. 



divisions of the brain also in these animals are identically 

 the same. The Brain of the Frog is notable principally 

 for the smaller size of its Cerebellum, and also for the 

 diminished bulk of its Optic Lobes and Olfactory Ganglia. 

 The Cerebral Lobes, are, therefore, proportionately large. 

 The Spinal Cord is shorter than usual, and does not 

 occupy the whole length of the ' spinal canal.' 



