78 



BRAIN AND BODY OF FISH 



THE SOLE 



In Plate 13 is an outline drawing of the brain of the sole seen from 

 above. The olfactory lobes are large and show some asymmetry, the 

 left overlapping the right ; the primitive end-brain is very large 

 and considerably larger than the ojDtic lobes which are definitely 

 small. The somatic-sensory lobes are large, and viewed from above 

 their outline has the appearance of two clubs with the narrower 

 ends tapering posteriorly and meeting in the middle line. The 

 cerebellum is of moderate size. Posterior to the somatic-sensory 

 lobes the vagal lobes are seen to be narrow and elongated. There 



PLATE 13. 



Sole. Lemon -dab 



p.e.b. — Primitive end-brain 

 Acoustic tubercles. 



Plaice. Witch. Dab. 



0.1. — Optic lobes. c.l.m. — Cerebellum, a.t.- 

 s.s.l. — somatic-sensory lobes, v. — Vagal lobes. 



is no sign of a facial lobe, although it does exist, but is very small 

 and completely hidden by other structures. 



When serial sections of the brain of a sole are examined it is 

 found that certain conclusions as to the significance of the lobes, 

 as would appear to be justified by naked-eye examination are not 

 confirmed. The medulla has been described as very long, and having 

 a pair of very prominent lobes (facial) upon its dorsal surface. 

 These are not facial lobes. Anterior to the vagal lobes, which are 

 narrow and not prominent, the facial lobes appear as small rounded 

 areas resting on the dorsal extremity of the vagals ; more anteriorly 

 fibres are seen passing ventrally and outwards from the facial lobes 

 into the gustatory tracts in the typical manner ; these lobes are 

 limited in extent both laterally and in an antero -posterior direction. 

 The facial nerves are small and do not enter the medulla until the 

 tip of the cerebellum appears in section, when they pass tranversely 



