FLAT-FISHES 91 



shcaped area of tissue, the free edge of which is lined with cihated 

 e})itheliuin beneatli wliich are small pear-shaped cells, and from 

 these fibres pass do^\■n^^•ards to enter a 'tine nervous meshwork. 



The acoustic tubercles are not prominent and there is no central 

 acoustic area. 



The cerebelhnn is characterized by the great extent of the stratum 

 granulosum which leaves only a small area of stratum moleculare. 

 When Me compare the similar sections of the megrim, we note that 

 the medulla is not so broad, but this is compensated by its greater 

 depth. It has well-marked somatic-sensory lobes and smaU facial 

 lobes A\liicli do not project so much into the wall of the rhomboid 

 fossa ; there are small acoustic tubercles and no central acoustic 

 area. The cerebellum is of the same type as that of the turbot, with 

 a very large area occupied by the stratum granulosum. If we com- 

 pare this picture with that of the second group it is seen that the 

 somatic-sensory lobes are more developed and that the facial lobes 

 are much smaller wliile the vagal lobes are more prominent. 



The food of the turbot, according to Cunningham, "consists almost 

 entirely of other fish. It is a predacious creature ; on the west 

 coast of Ireland the principal fish found in turbots stomachs were 

 sprats and sand-eels ; occasionally a dab, a sole, or a. pout." On 

 the trawling grounds of the south-west of England he found " in 

 the turbots stomachs the boar-fish known as the cuckoo, pilchards, 

 Mhiting, sea-bream and pout, never anything besides fish." 



The diet of the megrim, as of the turbot and brill, is fish, namely, 

 sprats, sand-eels, whiting, gobies, etc. We find here a group of 

 predacious fish, and the pattern of the brain is just what would be 

 expected. The optic lobes are large, the sensory-somatic lobes very 

 prominent and the facial lobes small — a condition comparable to 

 that found in the pollack, with this difference, that the facial lobe 

 is not apparent on a superficial examination, as they are completely 

 concealed by the overlapping of the somatic-sensory lobes. 



THE HALIBUT, Hippoglossus. 



Although the halibut belongs to the family Pleuronectidte and 

 has its eyes on the right side of the head, it is of a very different 

 build from the plaice, and has a very different habitat and diet. 

 Just as we have seen in the carps, that fish, though belonging to the 

 same family, may present a great variety of brain pattern, so in 

 the Pleuronectidse we shall find great differences in the pattern of 

 the medulla oblongata, according to their methods of feeding. 

 This is well shown when we contrast the brains of the hahbut and 

 plaice. 



