VALVULA CEREBELLI 130 



There is a central portion continuous with the cereljelhini and 

 two hiteral sausage-like lobes which are bent backwards on each 

 other so that their terniiuations turn rn wards towards their attach- 

 ments to the central lobe. The Trichiuridse Avhich include the 

 scabbard fishes are nearly related to the Scombriformes so it is not 

 sur])rising that they have also a special development of the valvula, 

 as A\e have demonstrated in serial sections of the Black scabbard 

 fish. When we come to the carps we find that in the ground- 

 feeding members of the family the tecta optica are more or less 

 widely separated by the protrusion of a large valvula, so that the 

 o])tic lobes are superficially very large and this is most marked in the 

 Barbel. 



As we have already noticed, MormjTus has a brain remarkable 

 for the immense development of the valvula which bursts through 

 the tectum opticum and forms a canopy over the whole brain. 

 To quote the R.C.S. catalogue, " this unusual relation of the valvula 

 cerebelli to the tectum opticum appears to be a further extension 

 of some such process as that seen in the carp, in which the lateral 

 parts of the tectum are divaricated and the central area much thinned 

 out, but without extrusion of the valvula. The wings of the valvula 

 are called anterior lateral and posterior. Their deep surface is 

 occupied by a layer of small cells (nuclear layer) covered over super- 

 ficially by a number of parallel ridges, each composed of molecular, 

 nuclear, intermediate, and fibrous layers." The result is of a very 

 beautiful design. 



We will now mention a fact of great importance, as will be seen 

 later, that the valvula is connected by tracts to the lobi inferiores, a 

 structiu"e which will be the subject of the next part of this chapter. 

 As to the function of the lobi inferiores, we have the authority 

 of Herrick for the statement that "the ascencUng secondary 

 gustatory tract of both facial and vagal lobes terminate in the 

 superior secondary gustatory nucleus, situate in the lateral wall 

 of the isthmus. The third chief gustatory tract arises from the 

 cortical layers of the above ; this tract is somewhat obscm*e, but 

 it has been proved that fibres pass from it ventrally to the lateral 

 lobule of the lobus inferior." He also gives a diagram showing 

 the relations of the olfactory and gustatory paths in teleosts in 

 which an olfactory conduction path terminates in the lobus inferior, 

 " this is the chief centre of correlation of olfactory and other 

 higher senses." 



